Features: brand new and high quality 2.1 Channel stereo output power 50watt x 2+100W, for working voltage range DC12-24V 4/8Ω passive speakers . Adopt professional ZK-MT21 module chip, with excellent sound quality. It ensures that even with high power operation for a long for time. Our Bluetooth-compatible board for amplifier audio's transmission efficiency is high and the transmission for path is wide. Support 3.5mm wired input, for high fidelity and powerful sound, with high transmission efficiency and wide transmission for path. With over-voltage for protection, under-voltage for protection, over-heat for protection, short-circuit for protection. for Ideal for DIY your passive speakers. Specifications: Product Name: Digital Power Amplifier Board Supply Voltage: DC12-24V Output Power: Left/Right Channel maximum <50W Subwoofer< 100W Maximum Power Per Channel: 100W Model Number: ZK-MT21 Channels: 3 (2.1) Size:approx 93 x 90 x 22mm/3.66x3.54x0.87in Material: Plastic Bluetooth: 5.0 (Unshielded 15M/49ft) Colour:Black Package Includes: 1 x Amplifier Board note: Only the above package content, other products are not included. Note: Light shooting 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.