Stackable Bluetooth Shield v2.1 (Slave only)

This Bluetooth shield is a serial port Bluetooth module (Slave) breakout board that uses the popular HC06 module. This shield plugs directly into the Arduino and uses the UART port for Bluetooth communication (slave mode only).Features:Switchable between 5V and 3.3V operationSimple UART serial connection (RX/TX connected to pins 0 and 1 of Arduino)DocumentationWiki