Fangrui Product Details Supports Bluetooth 5.1 Connectivity Support Bluetooth,aux,u Disk,usb,sound Card Input Over-temperature And Short-circuit Protection Against Static Electricity With Heat Sink Volume Can Be Adjusted Independently Features: Rich Button Functions, Simple Operation. Overheating, Overcurrent, Short Circuit, Anti-static For . App-control, You Can Set A Pass-word, Adjust The Volume Of The Prompt Sound, Switch The Prompt Sound, Etc. Box Pairing Function, The Wireless Function Enables Two Sets Of Speakers To Be Combined Into Left And Right Channel Pair Boxes, With A For Stronger Sense Of Spatial-positioning. Batch Differences May Lead To Product Appearance, Printed Text, Color Be Different, Does Not Affect The Use Of Color: Black Material: Pcb+metal Package Contents: 1 X Amplifier Board (need To Install Themselves) 1 X Screwdriver 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 T