Bluetooth 4.1 + EDR with a transmission distance of up to 10 meters; supports Bluetooth hands-free calling and A2DP stereo audio streaming. Supports TF card playback. Operating frequency: 2.4GHz. Certified by CE, FCC, and BQB. Features a 3.5mm stereo input jack, sleep mode for energy saving, and is powered via mini USB cable charging. When paired with your smartphone, the device automatically pauses audio playback during incoming or outgoing calls. Press the multi-function button to answer or end a call; audio resumes automatically after the call ends. Double-click the multi-function button to redial the last number. Reject an incoming call using the previous or next track buttons. Use the previous and next track buttons to select music. Press the multi-function button to pause or resume playback. Volume adjustment must be done on your connected device or car stereo, as the product does not have built-in volume controls. The receiver automatically reconnects to the last paired device upon power-on. For optimal performance, set your smart device to maximum volume. Low battery is indicated by a flashing red LED; charge promptly using a 5V/1A power source (e.g., HQX6 charger). The red light turns off when charging is complete. Material: ABS Color: Black Package Includes: 1 x Bluetooth adapter 1 x audio cable 1 x 3.5mm audio adapter Note: Light shooting and display differences may cause slight variations in color between the image and actual item. Measurement tolerance is +/- 1-3 cm. Content limited to items listed above; other accessories not included.