Audio transmitter receiving two in one 5.0 $ 7.15 Model: kn321 / kn319 Technology: kn321: bt5.0.kn319: bt4.2, A2DP, AVRCP ("receive only mode") Operating range: up to 10m / 33ft ("accessible") Matching name: kn321 / kn319 Loading time: 2 hours Working hours: Rx: 6 hours; TX: 5 hours Battery type: Li Polymer