1. Use PIC16f628a microcontrollers. 2. Do not need batteries,Power from the ignition. 3. Standard FUTABA plug(Black-Negative Red-Positive and White-Signal). 4. Using high-brightness LED digital tube. 5. Input voltage range:3.5V-8.4V. 6. Current consumption 25mA-60mA. 7. Mini tachometer indicates up to 30000 rpm. 8. Actual RPM= Display Digital *10 9. Body Size: 41mm L x 17mm W x 12mm H. 10.Window Size: 30mm L x 15mm H. 11.Weight:8.5g (0.3OZ) Instructions: 1.The Y wiring tandem between in the HALL sensor and the ignition. 2.The tachometer plug the other end with Y wire. 3.Connected to ignition power supply and can be displayed. Note: That connecting plugs do Reinforcement. To prevent vibration. The hall sensor & tachometer wire Leave from the Ignition high-voltage wire, And receiver wires over 30cm Connection tachometer is not recommended after the use of flight, Best to remove the Y wire to restore the original sensor connection If ignition have an additional tachometer pinout. You must be connected to dedicated tachometer signal wire.