Features Safety Guarantee: The protection mechanism includes overvoltage, undervoltage, overheating, DC detection, and short circuit protection, which is relatively safe Premium Performance: This power amplifier board has AUX+ Bluetooth audio input, subwoofer + left and right channel output, and the power amplifier chip has AM interference suppression function Excellent Material: This power amplifier board is made of high-quality material, which is strong and durable, has a long service life, and is more secure to use. Portable: The bluetooth power amplifier board is small in size, easy to carry and store, easy to use and has good performance Excellent After-sales Service: We provide you with high-quality after-sales service. If you have any questions, please feel free to contact us, and we will deal with it for you as soon as possible. Specification: Item Type: Power Amplifier Board Product Model: ZK-TB21 for Bluetooth Version: 5.0 (Unobstructed: Approx. 10meter / 32.8ft) Input Sensitivity: 500mV Input Method: AUX+ for Bluetooth Number of Channels: 2.1 channels Power Amplifier Chip: TPA3116D2 (with AM interference suppression function) Adapter Power Supply: DC 12-24 V/5A or more (the higher the voltage, the greater the output power) Adapted Speakers: 20-100W, 4-8Ω Output Power: Left and right channels <50W Subwoofer <100W Protection Mechanism: Overvoltage, undervoltage, overheating, DC detection, short circuit protection Package List: 1 x Power Amplifier Chip2 x Power Amplifier Board Module1 x Screw Accessories Pack1 x Screwdriver Accessories Pack Package List 1 x Power Amplifier Chip 2 x Power Amplifier Board Module 1 x Screw Accessories Pack 1 x Screwdriver Accessories Pack