VIKEFON BT-21 Bluetooth 5.0 Adapter Bluetooth Audio Transmitter Receiver 1. Bluetooth version: V5.0 2. Support protocol: RX supports A2DP, AVRCP, TX supports A2DP 3. Working frequency band: 2.402GHz-2.480GHz 4. Power level: Level 1 5. Sensitivity: -80dBm is less than 0.1% BER 6. Signal to noise ratio: greater than or equal to 75dB 7. Distortion: less than or equal to 0.1% 8. Support dual stream (TX mode supports one transmitter to connect two Bluetooth speakers or headphones at the same time to use one CODEC) 9. Support multi-point connection (RX mode supports connection of two mobile phones) 10. Codec mode: TX is apt-X HD, apt-X LL, apt-X, SBC; RX is apt-X HD, apt-X LL, apt-X, SBC 11. Note on using APTX: apt-X HD CODEC is preferentially supported in single connection (the connected device must also support apt-X HD) 12. Built-in battery: 1000mAh 13. Charging current: about 200mA 14. Charging time: about 4.5 hours 15. Life time: RX is greater than 20 hours, TX averages about 15 hours 16. Bluetooth distance: greater than 80m (straight line without obstruction) 17. Charging method: Micro USB 5V0.5A 18. Inputoutput connection: SPDIF interface, I2S AUX interface 19. Compatible: Android, IOS system phones, tablets and Bluetooth speakers or headphones that support A2DP protocol 20. Dimensions: 114 x 100 x 20mm 21. Weight: 270g