1. This trainer has two working modes. It can be used for CW training on computers and mobile phones. It is compatible with various operating systems and supports plug-and-play functionality without requiring additional drivers. To use this trainer with a mobile phone, an OTG adapter or OTG cable is required. 2. USB interface: Connects directly to a computer or mobile phone via an OTG device. 3. Key interface: Connects directly to manual keys and electronic keyers. To connect a manual key, connect the key first, then connect the trainer to the computer or mobile phone. The device automatically detects whether a manual key or electronic keyer is attached. 4. Mode button: Press and hold to switch between Mode 1 and Mode 2. In Mode 1, pressing and holding the button moves the cursor downward; holding it continuously at the bottom of the screen causes the cursor to move upward from the bottom — a useful function for mobile devices. 5. LED indicator: Shows current operating mode. Solid light indicates Mode 1, suitable for mouse-controlled CW training software or apps (e.g., Lakey, CWPlayer, MorseTrainer). Flashing light indicates Mode 2, suitable for specific CW training software or apps (e.g., VBand website, MorseMania, MorseIt). Name: CW Key Trainer Specification: USB interface Color: Green Material: Plastic Package Contents: 1 × CW Key Trainer Note: The package includes only the item listed above. Other accessories are not included. Note: Color may vary slightly due to screen settings and lighting conditions. Measurement tolerance: ±1–3 cm.