4in1 Bluetooth5.1 Transmitter Receiver Wireless USBAux Audio Transmitter Adapter Features: The 2 in 1 Bluetooth 5.1 audio receiver and transmitter is compatible for use on a wider range of devices. Rx mode can play music through the old style speaker/amplifier from mobile phone tablet. Tx mode supports working on TV computer. Update NFC function, touch to connect (mobile phone needs NFC function). With DSP chip, support bass and treble adjustment. Support FM radio function, 87.5-108MHz full frequency channel, you can automatically/manually search for channels. Built-in 6.5mm high-definition microphone, supporting microphone access for singing, and built-in anti-howling design. U disk/TF card playback, support MP3/WMA/SBC/WAV/DTS/A52/FLAC/AAC/AIF/AMR/APE music format. LCD screen display, status is clearly visible. Built-in 1200mAh rechargeable lithium battery, continuous listening to music for about 8 hours, battery life up to 30 days. IR remote control, can control the mode and volume. Specifications: Bluetooth version: Bluetooth V5.1 Supported protocol: A2DP/AVRCP/HSP/OPP/GATT/SM Working frequency band: 2.402GHz -2.480GHz Power level: Power level 2 (Class II) Sensitivity: -85dBm <0.1% BER Signal to noise ratio: ≥90dB Distortion: ≤0.1% Input interface: 3.5mm AUX/RCA/FM radio/USB/TF interface/6.5 MIC Output interface: 3.5mm AUX RCA Radio parameters: FM 87.5-108MHz Supported formats: MP3/WAV/WMA/APE/FLAC/G729/M4A/ALAC/AMR/DTS/MIDI/G726/MTY Screen size: 36*8 mm Working current: <40mA Built-in battery: 3.7V/1200mAh Charging current: about 1000mA (MAX) Charging time: about 1.5 hours Battery life: RX about 8 hours, TX about 8 hours Bluetooth distance: ≤30M (open place) Charging method: Type C 5V/1A Compatible devices: Mobile phones and PADs with Android and IOS systems, powered speakers, power amplifiers and Bluetooth speakers or earphones that support A2DP/ protocol. Notes: It will not show on the Bluetooth devices in your phone, computer or TV and you just need to bring the Bluetooth devices close to this Bluetooth transmitter, then they will be connected automatically. It is just a 2 in 1 Bluetooth audio transmitter receiver. Only can be used for audio transmission, so you can't use it for your keyboard, mouse or file transfer. Package List: 1x M9 Pro Bluetooth Audio Adapter 1x Bluetooth Antennas 1x FM Antenna 1x Type-C Charging Cable 1x RCA Cable 1x 3.5mm Aux Cable 1x Remote Control 1x User Manual