Usage Tips:Bluetooth Audio Receiver: Upgrade your non-Bluetooth speakers/home stereo/car stereo with this bluetooth adapter so you can enjoy wireless audio from your smartphone, tablet or laptop. Easy to set up and connect in seconds. interfaces and compatibility: support for optical fiber/RCA/3.5mm/AUX/U disk audio, to meet the needs of audio interface devices Easy Setup: This bluetooth receiver can be paired with your phone or tablet, and connected to non-bluetooth speakers/home stereo/car stereo via audio cable, then enjoy wireless music. Simple plug and play. Volume Control and Visual Indicators: Turn the knob to adjust the volume, press the "Less than" key to adjust the music track. Readable screen tells you mode and volume so you're never confused There is no battery in the Bluetooth adapter. Please connect the power supply before use. size: 90 x 77 x 30mm Material: ABS colour: black Package Contents: 1 x host 1 x 3.5 audio cable 1 x RCA connector 1 x Type-C power cord Only the above package content, other products are not included. Note: Light reflection 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. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.