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Black compact mechanical keyboard with red switches and RGB backlighting

Corn Electronics

Corn Electronics GK21S Gaming Keyboard Red Switch 750mAh

SKU CH-M5M9-TAGK8

A 21-key numpad kit with hot-swappable switches, Bluetooth 5.1 and wired dual-mode, per-key RGB and a 750 mAh battery

  • Key SwitchRed Switch
  • Keyboard ColorBlack

Key Switch Type Red Switch

Keyboard Color Black

  • 32-bit MCU delivers responsive input processing
  • 750mAh battery enables extended wireless sessions
  • Bluetooth 5.1 plus Type-C offers dual-mode connectivity
  • Hot-pluggable Kailh sockets allow switch changes without soldering
  • 8 million colour RGB with music rhythm reactive lighting

Compact Custom Mechanical Kit

The Corn Electronics GK21S is a numpad-sized mechanical keyboard kit aimed at enthusiasts who want to assemble a compact custom board. It ships with a 32 bit MCU and 8M flash for onboard firmware storage, plus a hot-pluggable Kailh connector so switches can be changed without soldering. Red linear switches are included and the PCB supports plate-mount stabilisers for a stable typing feel. Bluetooth 5.1 and a Type-C USB cable provide dual-mode connectivity for desktop or mobile use.

Check Compatibility Before Ordering

Verify that your operating system recognises standard HID keyboards over Bluetooth 5.1 or USB so the board works without extra drivers. The PCB accepts three-pin or five-pin MX-style switches including Cherry, BOX and Gateron types, so confirm your preferred switches match that footprint. Because the kit requires switch installation, ensure you have a switch puller and a clean workspace. The 750mAh battery charges over Type-C, so a USB power source is needed for wireless use.

Bundled Extras Expand Functionality

The 16.8 million colour per-key RGB array is driven by three 256-channel LED drivers and supports music rhythm and sound-reactive lighting effects. Onboard macro programming lets you define three custom layers directly on the device, useful for gaming shortcuts or productivity macros. Anti-RGB lamp positioning improves shine-through on compatible keycaps. No keycaps or stabilisers are included, so those must be sourced separately to complete the build.

Highlights

  • 32-bit MCU delivers responsive input processing
  • 750mAh battery enables extended wireless sessions
  • Bluetooth 5.1 plus Type-C offers dual-mode connectivity
  • Hot-pluggable Kailh sockets allow switch changes without soldering
  • 8 million colour RGB with music rhythm reactive lighting

Specifications

Key SwitchRed Switch
Keyboard ColorBlack

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Questions about this item

Does the GK21S kit include keycaps and switches, or must they be purchased separately?

The kit is a bare PCB with hot-pluggable Kailh sockets and plate-mount stabilisers; you need to supply your own MX-compatible switches and keycaps.

Should I choose the Bluetooth 5.1 or the Type-C wired mode for lowest latency?

Use the Type-C wired connection for the lowest latency; Bluetooth 5.1 is convenient for wireless use but adds slight overhead.

How long will the 750 mAh battery last with the 16.8 million colour RGB lighting active?

Battery life depends on brightness and effects; with full RGB the 750 mAh cell typically lasts several hours before needing a recharge via Type-C.

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