The module is designed for dialing keyboard and MCU interface.The module can instruct MCU(or keyboard)to generate 16 dual tones from Audio 1/2.The module equipped with two 3.5mm audio plug for same time using.Wide voltage range,you can connect it with voltage from 5~24VDC.There are 7 MCU input interface on the module.Working Voltage:5~24VDCWorking Current:6~8mAPower Port:2.1x5.5mm Female head male head DC power socketAudio Port:2x3.5mm Audio JackMCU Input Port: 7x 2.54mm Pin,5V GND D3 D2 D1 D0 STDColour: green + blackMaterial: plasticPackage Contents:1 * DTMF Generator Module1 * 50cm Male to Male 3.5mm Audio CordOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.