Bluetooth 4.1 + , transmission distance of 10m; Support Bluetooth hands-free call function; Support Bluetooth A2DP stereo sound Support TF card playback function; Frequency: 2.4GHz; CE, FCC, BQB certification 3.5mm stereo input jack; Sleep mode, energy saving; Power supply: use to charge When your smartphone is paired with the Bluetooth receiver; The product itself is not adjustable volume, you can adjust the volume on your phone or the volume of your car/stereo. Press the multi-function button to pause or resume playback. You can select your favorite music by using the previous song button or song button. Make/receive a call 1. When you dial a phone or answer an incoming call, the Bluetooth receiver will automatically pause the playback. 2. Press the multi-function button to end the call and your audio will resume playing automatically. Redial the last call Double click the multi-function button. Reject an incoming call You can reject an incoming call by either the previous button or Note 1. This Bluetooth receiver will automatically connect to the last paired device when it is used next time. 2. Please turn your smart device to the maximum volume when using. 3. If the Bluetooth receiver battery is low, the red indicator light will flash, please charge to HQX6 (5V / 1A input) in time, the red indicator light will be off when the charging is completed. Material:ABS colour:Black Package Contents: 1 x Bluetooth adapter 1 x cable 1 x audio adapter Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.