Easy to use with and Play capability Backward Bluetooth 2.0, 2.1, 3.0 and 4.0.5.0 specifications Transmitter Mode (TX) Red light: transfer audio from non Bluetooth device (tv, stereo, etc) to your Bluetooth headphones or speakers Receiver Mode (RX) Blue light: transfer audio from your Bluetooth device (headphones, speakers, etc) to your non Bluetooth device Supports multiple versions including XP, Vista, Win7, Win8, Win10