OSOYOO Bluetooth 4.0 HM-10 Master Slave Module for Xbee Arduino UNO R3 Mega 2560 Nano The most complete, most convenient, and most stable Bluetooth data transmission, remote control, and data acquisition module Master-slave in one, transparent transmission, replacing serial port Remote control, transparent transmission, MCU is unnecessary Remote data acquisition, transparent transmission, MCU is unnecessary Pls download the instructions: http://osoyoo.com/2016/10/27/bluetooth-4-0-hm-10-master-slave-module/