This product is a speaker-dependent voice recognition module. It supports up to 80 voice commands in all. Max 7 voice commands could work at the same time. Any sound could be trained as command. Users need to train the module first before let it recognizing any voice command. On V3, voice commands are stored in one large group like a library. Any 7 voice commands in the library could be imported into recognizer. It means 7 commands are effective at the same time. voltage: 4.5-5.5V digital interface: UART interface and GPIO 5V TTL level analog interface: 3.5mm mono microphone interface and microphone pin interface recognition accuracy: 99% (perfect environment) Colour:Orange+black Material: pcb Size:3.1 x 5cm Package Contents: 2 x Voice Recognition Module 2 x Microphone Only the above package content, other products are not included. Note: Light reflection 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.