Geeetech High Sensitivity Voice Recognition Module with Microphone + USB to RS232 TTL Converter + Jumper wires for Arduino Voice Module Voltage:4.5-5.5V. Voice Module Current:&lt;40mA. Voice Module Digital Interface: 5V TTL level UART interface,Recognition accuracy: 99% (under ideal environment). Voice Module Analog Interface: 3.5mm mono-channel microphone connector + microphone pin interface. Voice Module Size: 30mm x 47.5mm.