Features 1、Stepless Adjusting: The stepless tuning supports separate adjustment of subwoofer and stereo output volume, bringing you more enjoyment. 2、Clear Button Panel: The total volume knob is a mechanical potentiometer, also has clear volume position and rich multi function buttons. 3、Bluetooth Function: The bluetooth decoding chip has better resolution, which supports remote firmware update and for TWS function as well. 4、Varied Sound Modes: 10 kinds of sound modes with 2.1 sound channel will create pretty sound scenes for full mind and body relaxation. 5、Other Functions: Supports for Wuzhi Audio APP. Modify Bluetooth name, password settings, prompt tone volume adjustment, on off prompt tone, lullaby, firmware upgrade, etc. Specification Item Type: Audio Amplifier Board Model: MT21S Material: PCB, brass, ABS Purpose: For audio optimization. Features: Left and right channels 20-50w, 4-8 Ω subwoofer 20-100w, 4-8 Ω. Package List 1 x Audio Amplifier Board 2 x Cover Board 4 x Standoff 8 x Screw 5 x Knob Cover 1 x Plug 1 x Screwdriver