Features: ZK MT21 bluetooth-compatible digital amplifier module supports 24-bit/192kHz auditory decoding to provide excellent sound quality performances. Wide-spectrum compatible design Supports bluetooth-compatible 5.0 protocol, for wide ranges of devices, including smartphones, tablets and laptops Energy saving and high efficiency: Adopts Class D amplifier technology with up to 90% efficiency, effectively reducing energy consumption. Solve the heating problem of long time use, suitable for shops or exhibition venues that need to play background music for long time. Size is only 93x90x22mm, easy to integrate into various space layout. No need to take up too much space Easy installation not need for professional tools to complete the connection. Specifications: Model: ZK MT21 bluetooth-compatible Digital Amplifier Board Material: aluminum shell with good heat dissipation bluetooth-compatible version: 5.0 (no obstruction, 15meters) Input method: AUX+bluetooth-compatible Number of channel: 2.1channel Protections mechanism: Anti-reverse connection, overheating, overcurrent, short circuits protections Adaptived power supply: DC12~24V/5A or above (not connection to 24V battery pack) Output power: left and right channel less than 50W, subwoofer less than 100w Package Includes: 1Set ZK MT21 bluetooth-compatible Digital Amplifier Board note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.