brand new and high quality Features: 2.1-channel, personalized DIY active amplifier, more powerful and powerful to meet your picky hearing. TPA3110D2-Q1 is a 15W (per channel) high efficiency. Class D audio power amplifier for driving bridged stereo speakers. Advanced electromagnetic interference (EMI). Electromagnetic compatibility (for EMC). SpeakerGuard for protection circuit system. for DC detection circuit and output stage for protection. The TPA3110D2 can drive stereo speakers as low as 4 Ohm. It has over 90% efficiency when playing music. The output is fully protected against GND, VCC and output to shorts of output. Both short-circuit for protection and thermal for protection include automatic recovery. Power supply: DC8-20V Bluetooth:4.1 Size: 5x5.6cm/1.97x2.2inch Package includes: 1 x Bluetooth-compatible Subwoofer Digital Amplifier Board (without retail package)