Features: 1BLUETOOTH 5.0: Digital power amplifier module features Bluetooth 5.0 with a transmission range of up to 49 feet (unobstructed). Features a 3.5mm/0.1in AUX sound input jack. 2MORE LAYERED SOUND: Bluetooth power amplifier board by adjusting the high and low frequency knobs of for ZK MT21, you can make the sound more layered and the bass more shocking. 3CONVENIENT TO USE: Sound power amplifier board is easy to use, the DC adapter (plug size 5.5x2.1mm / 0.2x0.1in) on the market can basically meet the needs of for ZK MT21 Bluetooth power amplifier board. 4MULTIPLE PROTECTION MECHANISMS: Amplifier board has various protection mechanisms to ensure its safe operation. It has short circuit protection, over current, overheat and anti reverse protection. 5THOUGHTFUL DESIGN: When overload occurs, Bluetooth digital power amplifier module will report the fault condition to the processor to preserve itself from damage. Item Type: Bluetooth Digital Power Amplifier Module Material: PCB Sound Input: AUX And BT Voltage: DC12-24V Channel: 2.1 (50W, 50W, 100W) Bluetooth: 5.0 Current>9A Package Included: 1 x Bluetooth&nbspDigital&nbspPower&nbspAmplifier&nbspModule 2 x Housing 1 x DC Conversion Plug 1 x Screwdriver 4 x Studs 13 x Screw