MEMO CX21 Magnetic Phone Cooler with 18W Semiconductor Cooling, Dual Airflow, Fast Ice Cooling, RGB LED, Magnetic & Clip-On Design, USB-C for iPhone & Android

Keep your smartphone cooler during demanding mobile games, live streaming, recording, and other intensive workloads with the MEMO CX21 Magnetic Phone Cooler.

Designed as a high-performance mobile gaming cooler, the CX21 combines TEC semiconductor refrigeration with active fan cooling, allowing the cold plate to actively pull heat away from the rear of your smartphone while the fan and heatsink disperse that heat into the surrounding air. The CX21 is widely marketed as an 18W high-power cooler, while MEMO's current technical product page lists up to 20W power at 9V/2.2A, indicating that specifications can vary slightly between production batches.

The CX21 also features a 2-in-1 magnetic + clip-on mounting system, strong magnetic attachment, approximately 62–105mm clip compatibility, USB Type-C power, dynamic illuminated lighting, and a high-speed cooling fan. Its upward/downward airflow design helps direct exhaust away from the player's hands during extended gaming sessions.

Key Features

• High-Power Semiconductor Cooling – Marketed as an 18W gaming cooler, with MEMO's current technical documentation listing up to 20W maximum power depending on the production specification.
• TEC / Peltier Refrigeration – Actively transfers heat away from the phone instead of relying only on airflow.
• Fast Ice Cooling – Under suitable no-load test conditions, the cooling plate can drop below 0°C and may develop frost.
• 30 × 30mm TEC Cooling Chip – Current retail specifications identify a large 30mm × 30mm semiconductor cooling element.
• 2-in-1 Magnetic + Clip-On Design – Use direct magnetic attachment on compatible devices or install the supplied clips for broader phone compatibility.
• Strong Magnetic Attachment – Full-ring magnetic structure helps keep the cooler securely positioned on compatible phones.
• N52 Magnetic Core – Current CX21 retail listings specify an N52 neodymium magnetic system for strong attachment.
• Wide Phone Compatibility – MEMO specifies approximately 62–105mm phone width when using the clip mounting system.
• Dual / 3D Airflow Design – Upward and downward exhaust channels help move hot air away without directing as much heat toward the player's hands.
• High-Speed Cooling Fan – Manufacturer specifications list approximately 5500 RPM, while some current CX21 retail batches advertise up to approximately 6000 RPM.
• Dynamically Balanced Fan – Designed to reduce vibration and operating noise.
• Large Heat-Dissipation Area – MEMO lists approximately 3844mm² of heat-dissipation area.
• Illuminated Gaming Design – Integrated LED lighting adds a premium gaming appearance.
• USB Type-C Power – Convenient wired operation from a suitable charger or power bank.
• Plug-and-Play Operation – Connect power and start cooling without Bluetooth pairing or an app.
• Approx. 82g Weight – Lightweight enough for mobile gaming and portable use.
• No Internal Battery Required – Runs continuously while connected to a suitable power source.
• Ideal for Mobile Gaming – Useful for PUBG Mobile, Call of Duty Mobile, Genshin Impact, Warzone Mobile, Mobile Legends, emulation, and other demanding titles.

Specifications

MEMO's current technical page lists the CX21 with a Type-C interface, 9V/2.2A input, 20W maximum power, approximately 82g weight, 3844mm² heat-dissipation area, 5500 RPM fan, and 62–105mm clip compatibility.

Powerful TEC Semiconductor Refrigeration

The MEMO CX21 is not simply a fan blowing air over the back of your phone.

It uses a thermoelectric semiconductor cooling plate based on the Peltier effect.

The basic cooling process works in two stages:

1. The cold side of the TEC module absorbs heat from the phone.
2. The heatsink and fan move that heat away from the hot side of the cooler.

MEMO specifically describes the CX21 as using semiconductor electric cold-plate cooling to transfer smartphone heat into the cooling assembly before dissipating it into the surrounding air.

This active approach can provide significantly stronger surface cooling than basic fan-only mobile coolers.

High-Power 18W Cooling Class

The CX21 is sold widely as an 18W high-power mobile phone cooler, including current CX21 retail listings.

However, MEMO's current manufacturer page contains updated technical values stating:

• 9V / 2.2A
• 20W Power
• 20W Cooling Power

For an ecommerce listing, the safest wording is therefore:

“18W high-power CX21 model, with some manufacturer batches rated up to approximately 20W.”

The exact rating printed on the retail unit or packaging should be treated as the final specification for your stock.

Fast Ice Cooling

The high-power semiconductor system can cool the plate extremely quickly.

MEMO publishes a cooling-plate test range of approximately:

-7°C to -2°C at around 26°C ambient temperature.

Current retail testing also states that frost can develop at around 27°C room temperature when operated at 9V/2A under no-load conditions.

These figures are for the cooler's contact plate under controlled conditions.

They do not mean that:

• The smartphone CPU reaches -7°C.
• The battery reaches -7°C.
• Every phone will reach the same temperature.
• Frost is guaranteed during normal gaming.

Real-world cooling depends on the phone's heat output and operating conditions.

Helps Manage Thermal Throttling

Modern smartphones automatically reduce processor performance when internal temperatures become too high.

This process is known as thermal throttling.

During intensive gaming, throttling may result in:

• Lower Frame Rates
• Frame-Time Instability
• Sudden Performance Drops
• Lower Screen Brightness
• Reduced Charging Speed
• Hotter Surface Temperatures

External cooling can help move heat away from the smartphone chassis, potentially allowing the phone to operate in a more favorable thermal range.

The exact improvement depends heavily on the phone model, game, settings, room temperature, and cooler placement.

30 × 30mm TEC Cooling Chip

Current CX21 retail specifications identify a large 30 × 30mm TEC semiconductor cooling element.

A relatively large cooling module provides a substantial contact area for transferring heat away from the smartphone.

For best results, the cold plate should be positioned as close as practical to the phone's main heat-generating region.

Large Heat-Dissipation Area

MEMO specifies a heat-dissipation area of approximately:

3844mm².

The heatsink area works together with the fan to dispose of the heat pulled away from the phone by the semiconductor module.

This combination is important because a TEC system can only continue cooling effectively if heat is removed efficiently from its hot side.

Dual / 3D Airflow Design

The CX21 uses an airflow layout that directs hot exhaust upward and downward rather than concentrating it directly toward the player's hands.

This can improve comfort during long mobile gaming sessions.

The airflow architecture is especially useful when playing in landscape orientation, where your hands normally sit close to both sides of the phone.

High-Speed Cooling Fan

MEMO's technical page lists the CX21 fan at approximately:

5500 RPM.

Some newer retail listings quote fan speeds of up to approximately:

6000 RPM.

The high-speed fan continuously moves hot air away from the heatsink, allowing the semiconductor cooling system to keep operating effectively.

Dynamically Balanced Fan Design

MEMO describes the CX21 fan as being dynamically balanced to reduce vibration during rotation.

Reduced fan vibration can be particularly useful during:

• Competitive Gaming
• Live Streaming
• Voice Chat
• Screen Recording
• Long Gaming Sessions

because excessive vibration could otherwise affect comfort or microphone pickup.

Low-Noise Cooling

MEMO's specification table lists approximately 35–38dB fan noise, although another marketing section on the same manufacturer page claims lower operating noise.

Because these figures conflict internally, 35–38dB should be treated as the more conservative published specification.

Noise levels can also vary depending on:

• Fan Speed
• Mounting Surface
• Power Input
• Measurement Distance
• Production Batch

2-in-1 Magnetic + Clip-On Design

The CX21 provides two mounting options:

Magnetic Installation

Compatible magnetic smartphones and cases can attach directly to the cooler.

MEMO describes the internal magnetic structure as a full circle of strong magnets that holds the cooler tightly against the phone.

Current retail versions further describe the magnetic system as using N52 neodymium magnets.

Benefits include:

• Fast Installation
• Easy Removal
• No Side Clamps
• Clean Appearance
• Easy Repositioning

Clip-On Installation

For smartphones that do not support direct magnetic mounting, the CX21 also supports detachable back clips.

MEMO officially specifies compatibility with phones approximately:

62–105mm wide.

This allows the CX21 to work with a much broader range of Android smartphones and iPhones.

Broad iPhone Compatibility

Magnetic attachment makes the CX21 especially convenient for compatible iPhones or MagSafe-compatible cases.

It can be useful for demanding iPhone gaming workloads such as:

• PUBG Mobile
• Call of Duty Mobile
• Genshin Impact
• Warzone Mobile
• Mobile Legends
• Racing Games
• Console Emulation

For phones or cases without suitable magnetic support, use the clip attachment.

Broad Android Compatibility

The clip system extends compatibility to many Android phones from brands such as:

• Samsung
• Xiaomi
• Redmi
• POCO
• OnePlus
• OPPO
• realme
• HONOR
• Huawei
• ASUS ROG Phone
• REDMAGIC

Physical compatibility depends on the device's:

• Width
• Camera Position
• Rear Shape
• Case Thickness

MEMO's official width specification is approximately 62–105mm.

USB Type-C Powered

The CX21 uses a USB Type-C power interface.

This makes it convenient to power from compatible:

• USB Wall Chargers
• Power Banks
• Desktop Chargers
• Powered USB-C Supplies

For maximum cooling, the power source must be capable of providing the required voltage and current.

Use a Proper Power Adapter

The CX21's strongest cooling mode requires substantially more power than basic 5V smartphone fans.

Current versions specify approximately:

9V / 2A to 2.2A.

A weak USB port or old low-power adapter may allow the fan to operate but may prevent the TEC cooler from reaching full cooling performance.

For best results, use a compatible power adapter that can supply the required 9V output.

No Built-In Battery

The CX21 is a plug-in phone cooler rather than a rechargeable battery-powered cooler.

Advantages include:

• No Internal Battery to Recharge
• Continuous Cooling While Powered
• No Battery Aging Inside the Cooler
• Better Suitability for Long Gaming Sessions

For portable gaming, pair it with a suitable power bank capable of providing the required output.

Gaming LED Lighting

The CX21 includes illuminated lighting designed to add a more distinctive gaming appearance.

MEMO's current specification table refers to RGB lighting, although another section on the manufacturer page describes a single-color purple streaming effect, suggesting that lighting configuration may differ between CX21 batches.

For ecommerce accuracy, listing it as “RGB / illuminated gaming lighting” is safest unless the exact retail box confirms a specific lighting pattern.

Great for PUBG Mobile

PUBG Mobile can place continuous load on the smartphone CPU and GPU, especially when using:

• High Frame Rates
• High Graphics
• Long Matches
• Voice Chat
• Screen Recording

The MEMO CX21 is designed specifically for this kind of sustained gaming workload.

Its active cooling can help remove heat from the rear surface while you play.

Great for Call of Duty Mobile

The CX21 is also useful for high-FPS games such as Call of Duty Mobile.

Suitable for:

• Multiplayer
• Ranked Matches
• Battle Royale
• Long Competitive Sessions
• Screen Recording
• Streaming

Cooling cannot increase the phone's fundamental hardware capability, but it can help reduce the conditions that cause thermal throttling.

Great for Genshin Impact

Graphically demanding open-world games are especially challenging for smartphone cooling systems.

The CX21 can be useful during:

• High Graphics Settings
• Long Exploration Sessions
• Combat
• High Refresh Rate Play
• Charging While Gaming

Great for Warzone Mobile

Games with console-style visuals and large multiplayer maps can generate significant processor heat.

The CX21's TEC cooling system is designed for exactly these high-load scenarios.

Great for Mobile Legends & MOBA Gaming

Even games that are not as graphically intensive can warm a phone over multiple consecutive matches.

The CX21 can also be useful for:

• Mobile Legends
• League of Legends: Wild Rift
• Honor of Kings
• Arena of Valor

The cooler's exhaust design can also help keep hot airflow away from the player's hands.

Useful for Mobile Emulation

Console and PC emulation can place extremely heavy continuous load on mobile processors.

The CX21 can therefore also be useful for:

• Retro Emulation
• PS2 Emulation
• GameCube Emulation
• Switch-Style Emulation Workloads
• Windows / PC Emulation

Cooling effectiveness will vary greatly by device and emulator.

Useful for Live Streaming

Gaming is not the only workload capable of heating a smartphone.

The CX21 can also be useful for:

• TikTok Live
• YouTube Live
• Facebook Live
• Mobile Game Streaming
• Long Video Calls
• Screen Recording

Streaming can use the processor, display, network connection, camera, and encoder simultaneously.

Useful for Video Recording

Extended high-resolution video recording can also generate significant smartphone heat.

The CX21 can help cool the rear chassis during stationary recording setups, provided it does not obstruct:

• Camera Lenses
• Microphones
• Stabilizer Mounts
• Tripods

Compact & Lightweight

MEMO lists an official net weight of approximately:

82g.

A current retail listing gives a nearly identical 81.5g figure.

This keeps the cooler relatively lightweight for:

• Travel
• Gaming Bags
• Backpacks
• Mobile Esports Events
• Portable Gaming Setups

Perfect For

• iPhone Gaming
• Android Gaming
• PUBG Mobile
• Call of Duty Mobile
• Warzone Mobile
• Genshin Impact
• Mobile Legends
• High-FPS Gaming
• Mobile Esports
• Gaming Phones
• Competitive Mobile Gaming
• Mobile Streaming
• Screen Recording
• Video Recording
• Emulation
• Mobile Gaming Controllers
• Gaming Events
• RGB Gaming Setups
• Long Gaming Sessions

Why Choose the MEMO CX21 Magnetic Phone Cooler?

• High-power 18W-class semiconductor cooling.
• Manufacturer specifications up to approximately 20W on current version.
• TEC / Peltier refrigeration technology.
• Approximately 30 × 30mm TEC chip.
• Fast cooling response.
• Capable of sub-zero cold-plate temperatures under suitable no-load conditions.
• Approx. 3844mm² heat-dissipation area.
• High-speed active cooling fan.
• Approximately 5500 RPM official fan specification.
• Some current versions advertise up to around 6000 RPM.
• Dynamically balanced fan.
• Upward/downward 3D airflow.
• Helps keep exhaust heat away from hands.
• Strong full-ring magnetic mounting.
• N52 magnetic design on current retail variant.
• 2-in-1 magnetic + clip mounting.
• Approx. 62–105mm clip compatibility.
• USB Type-C power.
• 9V high-power operation.
• RGB / illuminated gaming effect.
• Approx. 82g lightweight design.
• Plug-and-play operation.
• No built-in battery.
• Suitable for iPhone.
• Suitable for Android.
• Great for PUBG Mobile.
• Great for Call of Duty Mobile.
• Great for Genshin Impact.
• Useful for streaming and recording.
• Brand: MEMO.
• Model: CX21.

Package Contents

MEMO's manufacturer specification lists:

• 1 × MEMO CX21 Phone Cooler
• 1 × Pair of Phone Clips
• 1 × Approx. 1m USB Type-C Power Cable
• 1 × User Manual
• Retail Packaging

Some retailer bundles include additional clips, magnetic plates, or promotional accessories, so those extras should only be listed if they are physically included with your exact retail batch.

Important

Power Rating: The CX21 is widely sold as an 18W model, matching this product title. However, MEMO's current technical page also lists 9V/2.2A and 20W maximum power/cooling power. This appears to represent a specification or production-batch revision. For your final ecommerce specification, the rating printed on your actual CX21 box or unit should take priority.

Cooling Temperature: MEMO's sub-zero temperature figures refer to the cold plate under controlled testing, not the smartphone's CPU or battery temperature.

Condensation Warning: High-power semiconductor cooling can make the plate colder than the surrounding air's dew point. This can cause moisture or frost to form. Do not allow condensation to enter the smartphone's ports, camera assembly, cooler electronics, or other accessories.

Phone Cases: Thick or insulating cases can reduce heat transfer significantly. For maximum cooling, direct contact with the phone or a thin thermally suitable surface is preferable.

Magnetic Compatibility: Phones without built-in magnetic mounting require the supplied clip system or a suitable magnetic plate/ring.

Wireless Charging: The CX21 is a cooling accessory, not a wireless charger.

Lighting Note: MEMO's current product page contains conflicting descriptions of the lighting as both RGB and single-color purple streaming illumination. Lighting behavior may therefore vary by production batch.