1、Adopts low noise preamp, shielded power inductor, and 3116 amplifier chip, can provide stable and quick connection, with wide compatibility. 2、This audio amplifier module has two audio input modes: one is the BT input mode, another is the AUX input mode, BT mode priority. 3、BT mode: no matter in which mode the BT can be connected, as long as the BT connection is successful it is the BT mode, and BT mode supports automatic back to connect. 4、AUX mode: BT no connection when AUX is inserted is AUX mode, it should be noted that when using AUX mode, you need to confirm that the BT connection of this module has been disconnected. 5、Master volumes adjustment function: The VOLUMEs knob on the right is to adjust the master volumes, right rotation of the master volumes increases, left rotation of the master volumes decreases. The master volumes has an effect on the volumes of both the left and right channels and the subwoofer. 6、Bass adjustment: The BASS potentiometer in the middle is to control the bass, right-hand rotation bass enhancement, left-hand rotation bass attenuation. When the knob is in the middle position, the bass is not enhanced nor attenuated. 7、Treble adjustment: The TREBLE potentiometer on the left is to control the treble, right turn treble enhancement, left turn treble decay. When the knob is in the middle position, the treble is not enhanced and not attenuated. 8、Multiple protections: over-voltage, under-voltage, overheating, direct current detection, short-circuit protections, safer to use. This is a BT audio amplifier module which has sound volumes adjustment, high and bass independent adjustment, BT + AUX audio input, dual-channel stereo output, with overheating, overcurrent, short-circuit protections mechanism. The higher the supplying voltage the higher the output power, the smaller the speaker impedance the higher the output power. Features: Adopts low noise preamp, shielded power inductor, and 3116 amplifier chip, can provide stable and quick connection, with wide compatibility. This audio amplifier module has two audio input modes: one is the BT input 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 the BT connection is successful it is the BT mode, and BT mode supports automatic back to connect. AUX mode: BT no connection when AUX is inserted is AUX mode, it should be noted that when using AUX mode, you need to confirm that the BT connection of this module has been disconnected. Master volumes adjustment function: The VOLUMEs knob on the right is to adjust the master volumes, right rotation of the master volumes increases, left rotation of the master volumes decreases. The master volumes has an effect on the volumes of both the left and right channels and the subwoofer. Bass adjustment: The BASS potentiometer in the middle is to control the bass, right-hand rotation bass enhancement, left-hand rotation bass attenuation. When the knob is in the middle position, the bass is not enhanced nor attenuated. Treble adjustment: The TREBLE potentiometer on the left is to control the treble, right turn treble enhancement, left turn treble decay. When the knob is in the middle position, the treble is not enhanced and not attenuated. Multiple protections: over-voltage, under-voltage, overheating, direct current detection, short-circuit protections, safer to use. Specifications: Name: BT Audio Amplifier Module BT version:5.0 (unobstructed, 10 meters) Signal noise ratio: ＞90dB Input mode: AUX+BT Number of channels: Left and right dual channel (stereo) Power amplifier chip: TPA3116D2 (with AM interference suppression function) Adaptable power supplys: DC9-24V/2A or more (the higher the voltage, the higher the output power) Applicable speakers: 15-100W, 4-8Ω Output power: 15W*2 @12V,8Ω 30W*2 @12V,4Ω 20W*2 @19V,8Ω 40W*2 @19V,4Ω 30W*2 @24V,8Ω 50W*2 @24V,4Ω Protections mechanism: over-voltage, under-voltage, overheating, Direct current detection, short-circuit protections Item size: 110 * 70 * 21mm / 4.33 * 2.76 * 0.83in Item weight: 113g / 3.99ounce Package size: 150 * 100 * 50mm / 5.91 * 3.94 * 1.97in Package weight: 154g / 5.43ounce Packing List: 1 * BT Audio Amplifier Module 1 * Screwdriver 1 * Cable 1 * BT Audio Amplifier Module 1 * Screwdriver 1 * Cable