Bluetooth 4.1 + EDR with a transmission distance of up to 10 meters; supports Bluetooth hands-free calling and A2DP stereo audio streaming. Support for TF card playback function; operating frequency: 2.4GHz; certified by CE, FCC, and BQB. Equipped with a 3.5mm stereo input jack; features sleep mode for energy saving; powered via mini USB cable charging. When paired with a smartphone, the device enables wireless audio streaming; volume control is managed through the connected phone or car stereo, as the receiver itself does not have volume adjustment. Press the multifunction button to pause or resume playback; use the previous or next track buttons to select music. Answer or end calls with the multifunction button; double-click to redial the last number; reject incoming calls using the previous or next track buttons. Auto-reconnects to the last paired device upon power-on. Ensure the connected smart device is set to maximum volume during use. Low battery is indicated by a flashing red LED; charge using a 5V/1A adapter (not included); the red light turns off when fully charged. Material: ABS Color: Black Package Contents: 1 x Bluetooth adapter 1 x audio cable 1 x 3.5mm audio adapter Note: The package includes only the items listed above. Lighting and display differences may cause slight color variations between the image and the actual product. Measurement error allowed is +/- 1-3 cm.