Bluetooth Module HC-06 4 pin

From the shop's description

Allows your device to both send or receive the TTL data via Bluetooth technology without connecting a serial cable to your computer. Works with any USB Bluetooth adapters. Default Baud Rate: 9600,8,1,n. Built in antenna. Coverage up to 30ft. Bluetooth version: V2.0 EDR Operating voltage: 3.3V Default Baud Rate: 9600,8,1,n. Signal coverage: 30ft Item size: 4.3 * 1.6 * 0.7cm Item weight: 3g Package size: 9 * 3 * 1cm Package weight: 8g Commercial Series: Bluetooth module board Series With LED indicator light, use 150mA and 3.3V regulation chip. With VCC.GND.TXD.RXD foot for the Bluetooth With “Re-seach” button(ON/OFF/WAKE foot for it , external MCU outinput “High level” can control module to re-seach) Compatible with bluetooth master module”.slave module”or master-slave(whole) module. Input voltage: 3.3~6V Size: 1.55cm*3.98cm Note: input power supply 3.3~6V, Prohibit more than 7V No “Automatically prevent power supply peversing func”, so please correctly connect power supply We advise to install “Bluetooth master module” The “State” is output foot for LED status, when bluetooth “Unconnected”, output “Pulse” ; when bluetooth “connected”, output “High level”, we can determine the states from “MCU” If only the board , No any “Bluetooth Function “