1. Introduzione
This manual provides instructions for the KEYCOOL K21 Mechanical Number Keypad. The K21 is a versatile 21-key numeric keypad designed for enhanced productivity across various operating systems. It features triple-mode connectivity, hot-swappable switches, customizable RGB lighting, and programmable keys.

Figura 1: Fronte view of the KEYCOOL K21 Mechanical Number Keypad showcasing la sua illuminazione RGB.
2. Impostazione
2.1 Contenuto della confezione
Prima di procedere, assicurati che tutti gli elementi siano presenti:
- KEYCOOL K21 Mechanical Number Keypad
- Cavo USB-C
- Ricevitore USB a 2.4 GHz
- Estrattore per tasti
- Estrattore per interruttori
- Spare Switches (if included)
- Manuale dell'utente (questo documento)

Figure 2: Standard accessories included with the K21 keypad.
2.2 Ricarica della tastiera
The K21 keypad is equipped with a 1500mAh battery. For optimal performance, fully charge the keypad before first use.
- Locate the USB-C port on the keypad.
- Connect the provided USB-C cable to the keypad and to a power source (e.g., computer USB port, USB wall adapter).
- The charging indicator light will illuminate. It will change or turn off once fully charged.
2.3 Modalità di connettività
The K21 supports three connection modes: Wired, 2.4GHz Wireless, and Bluetooth 5.0.

Figure 3: Location of connectivity components on the K21 keypad.

Figure 4: Detailed diagram of the keypad's connection points.
2.3.1 Modalità cablata
- Ensure the keypad's ON/OFF switch is in the "OFF" position.
- Connect the USB-C cable to the keypad's Type-C port and to your computer.
- The keypad will be automatically recognized by your system.
2.3.2 Modalità wireless a 2.4 GHz
- Locate the 2.4GHz USB receiver, usually stored in a dedicated slot on the keypad.
- Collega il ricevitore USB da 2.4 GHz a una porta USB disponibile sul tuo computer.
- Turn the keypad's ON/OFF switch to the "ON" position.
- La tastiera dovrebbe connettersi automaticamente.
2.3.3 Modalità Bluetooth 5.0
The K21 can connect to up to three Bluetooth devices.
- Turn the keypad's ON/OFF switch to the "ON" position.
- Press and hold the Bluetooth pairing key (refer to the keypad layout for specific key, often indicated by a Bluetooth icon or a combination with Fn).
- La spia luminosa lampeggerà, indicando la modalità di associazione.
- On your device (Laptop, Mac, Win, iOS, Android), go to Bluetooth settings and search for "KEYCOOL K21" or similar.
- Select the keypad to pair. Repeat for other Bluetooth profiles se lo si desidera.
2.4 Design ergonomico
The K21 wireless numeric keypad features a sloped design for comfortable use and includes silicone bottom cushions for stability.

Figure 5: Ergonomic design and dimensions of the K21 keypad.
3. Funzionamento
3.1 Funzioni base dei tasti
The K21 is a 21-key numeric keypad. Standard numeric and arithmetic functions are available. Some keys may have secondary functions accessible via the Function (Fn) key.

Figura 6: Oltreview of the K21 keypad's features.
3.2 Controllo dell'illuminazione RGB
The K21 features adjustable RGB lighting effects.
- Fn + Back: Turn ON/OFF the backlight.
- Fn + 6: Switch between different lighting effects.
- Fn + 7: Switch between different lighting colors.

Figure 7: Key combinations for controlling RGB lighting and hot-swappable switch design.
Rullo a 3.3 volumi
The integrated volume roller allows for quick adjustment of system audio. Rotate the roller to increase or decrease volume. The roller may also have a press function for mute/unmute.
4 Personalizzazione
4.1 Switch sostituibili a caldo
The K21 keypad supports hot-swappable 3-pin/5-pin mechanical switches, allowing users to change switches without soldering. This enables customization of typing feel and sound.
- Using the provided switch puller, carefully remove the desired switch by gripping it firmly and pulling upwards.
- Allineare i pin del nuovo interruttore con i fori sul PCB.
- Gently press the new switch into place until it clicks. Ensure it is seated properly and not bent.

Figure 8: Illustration of a hot-swappable switch being installed.

Figure 9: Components and characteristics of a typical mechanical switch.
4.2 Programmable Keys and Software
The K21 keypad features programmable keys, allowing users to customize key functions, macros, and lighting effects via dedicated software.
- Download the official KEYCOOL K21 software from the manufacturer's websito: www.kc-keycool.com.
- Installa il software sul tuo computer Windows o Mac.
- Connect the K21 keypad to your computer via wired mode.
- Launch the software to access customization options for key remapping, macro creation, and RGB lighting adjustments.

Figure 10: Software interface for personalizing key functions and lighting.

Figure 11: Further views of the customization software.
5. Manutenzione
5.1 Pulizia
To maintain the keypad's appearance and functionality:
- Disconnect the keypad from all power sources and devices.
- Utilizzare un panno morbido e privo di lanugine dampened with a small amount of water or a mild cleaning solution to wipe the keycaps and casing.
- Per rimuovere polvere e detriti tra i tasti, utilizzare aria compressa o una piccola spazzola.
- Evitare l'uso di prodotti chimici aggressivi o materiali abrasivi.
5.2 Cura degli interruttori e dei tasti
The PBT keycaps are durable. If removing keycaps or switches for cleaning or replacement, use the provided tools to prevent damage.
6. Risoluzione Dei Problemi
6.1 La tastiera non risponde
- Modalità cablata: Ensure the USB-C cable is securely connected to both the keypad and the computer. Try a different USB port or cable.
- Modalità wireless a 2.4 GHz: Verify the 2.4GHz USB receiver is properly inserted into a USB port. Ensure the keypad's ON/OFF switch is in the "ON" position.
- Modalità Bluetooth: Check if the keypad is paired correctly in your device's Bluetooth settings. Ensure the keypad's ON/OFF switch is in the "ON" position. If the keypad goes to sleep, the first key press might not register; press a key twice to wake it up and ensure connection.
- Batteria: Ensure the keypad is sufficiently charged. Connect it via USB-C to charge.
6.2 Problemi di illuminazione RGB
- If RGB lighting is not working, ensure it is turned on using Fn + Back.
- If specific keys are not lighting up, check if the switches are properly seated or if there's a software configuration issue.
6.3 Software Not Detecting Keypad
- Ensure the keypad is connected via wired mode when using the software.
- Verify that you have downloaded the correct software version for the K21 model from the official KEYCOOL websito.
- Try restarting your computer and the software.
- If the device is listed as "Unknown Device" in Device Manager (Windows), try reinstalling the driver or checking for driver updates.
6.4 Durata della batteria scarsa
- High RGB brightness and continuous wireless usage can reduce battery life. Consider adjusting brightness or using wired mode when possible.
- Assicurarsi che la tastiera sia completamente carica prima dell'uso.
7. Specifiche
| Caratteristica | Dettaglio |
|---|---|
| Modello | K21 |
| Marca | CHIAVE COOL |
| Connettività | Bluetooth 5.0, wireless a 2.4 GHz, USB-C cablato |
| Tipo di tastiera | Meccanico |
| Conteggio delle chiavi | 21 Chiavi |
| Interruttori | Hot-Swap (compatibile con 3 pin/5 pin) |
| keycaps | PBT (Heat-sublimation) |
| Retroilluminazione | RGB (personalizzabile) |
| Capacità della batteria | 1500mAh |
| Tasso di sondaggio | 1000 Hz |
| Sistemi compatibili | Windows, Mac, Linux, Android, iOS |
| Caratteristiche speciali | Backlit, Hot-Swappable, Portable, Volume Roller, Gasket Mount |
| Dimensioni del prodotto | 3.62 x 5.35 x 1.61 pollici (circa) |
| Peso dell'articolo | 12 once |
| Materiale | Plastic, Polybutylene Terephthalate |
Table 1: Technical specifications of the KEYCOOL K21 Mechanical Number Keypad.

Figure 12: Visual representation of KEYCOOL K21 specifications and multi-device compatibility.
8. Dimostrazione video
Video 1: Un video dimostrativo ufficiale mostraasing the unboxing, switch replacement, and typing sound of a KEYCOOL mechanical keyboard. This video provides a visual guide to the product's features and user experience.