This is a BT audio amplifier module with high and bass independentadjustment, BT + AUX audio input, dual-channel stereo output, withoverheating, overcurrent, short-circuit protections mechanism. The higherthe supplys voltage the higher the output power, the smaller the speakerimpedance the higher the output power. Features: Adopts low noise preamp, shielded power inductor, large capacity energystorage capacitor and 3116 amplifier chip, can provide stable and quickconnection, with wide compatibility. This audio amplifier module has two audio input modes: one is the BTinput mode, another is the AUX input mode, BT mode priority. BT mode: no matter in which mode the BT can be connected, as long as theBT connection is successful it is the BT mode, and BT mode supportsautomatic back to connect. AUX mode: BT no connection when AUX is inserted is AUX mode, it shouldbe noted that when using AUX mode, you need to confirm that the BTconnection of this module has been disconnected. Main volumes adjustment function: MAIN-VOLUME knob is to adjust themain volumes, right rotation of the main volumes increases, left rotation ofthe main volumes decreases. The main volumes has an effect on thevolumes of both the left and right channels and the subwoofer. Bass adjustment: R&L CHANNEL-BASS knob is to control the bass, right-hand rotation bass enhancement, left-hand rotation bass attenuation. When the knob is in the rightmost position, the bass is not enhanced norattenuated. Treble adjustment: R&L CHANNEL-TREBLE knob is to control the treble,right turn treble enhancement, left turn treble decay. When the knob is inthe middle position, the treble is not enhanced and not attenuated. Subwoofer volumes adjustment: SUBWOOFER-VOLUME knob is to controlthe volumes of the subwoofer. The volumes becomes louder with rightrotation and smaller with left rotation. Subwoofer cut-off frequency adjustment: SUBWOOFER-FREQ knob is tocontrol the subwoofer cut-off frequency. The frequency of right rotationincreases and the frequency of left rotation decreases. Frequencyadjustment ranges of 20Hz-200Hz. Multiple protections: over-voltage, under-voltage, overheating, direct currentdetection, short-circuit protections, safer to use. Specifications: Name: 50W*2 BT Audio Amplifier Module BT version: 5.0 (unobstructed, 10 meters) Input sensitivity: 500mV Input mode: AUX+BT Number of channels: 2.1 Power amplifier chip: TPA3116D2 (with AM interference suppressionfunction) Adaptable power supplys: DC12-24V/5A or more (the higher the voltage, thehigher the output power) Applicable speakers: 20-100W, 4-8 Output power: left and right channels 50W; subwoofer 100W Protections mechanism: over-voltage, under-voltage, overheating, direct current detection, short-circuit protections Item size: 118 * 100 * 22mm / 4.65 * 3.94 * 0.87in Item weight: 195g / 6.88ounce Package size: 150 * 140 * 50mm / 5.91 * 5.51 * 1.97in Package weight: 256g / 9.03ounce Packing List: 1 * BT Audio Amplifier Module 1 * Screwdriver