Feature: 1. MAIN PURPOSE: 4 independent buttons keyboard module, for student class design graduation project experiment. 2. EXCELLENT PCB: The keyboard switch module adopts 1.6mm thick PCB double sided board, which is sturdy and durable. 3. SAFE OPERATION: The key module has a large heat dissipation area, stable and reliable, suitable for long term operation. 4. REASONABLE DESIGN: The amp circuit has been repeatedly debugged, with reasonable component layout and less interference. 5. EASY TO INSTALL: The keyboard module has mounting holes, with compact structure, easy to install and disassemble. Specification: Item Type: Keyboard Module Material: PCB Number of Keys: 4 Keys Number of Pins: 4 Pin Package List: 1 x Keyboard Module