1, 5.0 bluetooth version, transmission efficiency is higher, transmission distance is .2. size heat sink ensures efficient heat dissipation.3, potentiometer to adjust the volume, with a switch, easy to control the volume, suitable for DIY speakers.If it is a metal box, you need to draw out the bluetooth antenna. 4. Copper DC connector is adopted to withstand high current and no heat.5. 4*470uF green gold capacitor guarantees the power storage capacity and the continuous and stable power supply is the premise of good sound quality. 6. The DC head with cable can be compatible with the input power interface of this product. Even if you 't have the DC head adapter or battery, you can connect it . Adaption Supply Voltage: 5-24V (9V/12V/15V/18V/24V adapter, recommended high voltage) Power Supply Voltage: 12V------8hom speaker/24W (Left channel) + 24W (Right channel), 4 ohm speaker/40W + 40W,15V------8homs /32W + 32W, 4 ohm/ 60W + 60W,19V------8homs /64W + 64W, 4 ohm/ 80W + 80W,24V------8homs /72W + 72W, 4 ohm/ 100W + 100W Parameter: Product Name:HIFI with filter 2X100W Bluetooth digital power amplifier board Model: -1002L Chip Solution: domestic With or Without Filter: Yes Adapter Speaker: 50W-300W, 4 ohm-8 ohm Number of Channels: Left and right stereo (Stereo) Bluetooth Version: 5.0 Bluetooth Transmission Distance: 15m(Without occlusion) Protection Mechanism: Overheating protection,Short Circuit protection colour:black Material:Metal +pc Package Contents: 1* Bluetooth 5.0 Digital Amplifier Board 1* shell 1* screwdriver 1* power cord Notes for use: the power switch on the board is standby switch, and the machine is in standby state with low power consumption after the switch is turned off. Tocompletely turn off the power or to remove the DC plug on the machine for a long time, it is ok. Tip: To have enough output power if the audio input is sufficient and the supply voltage/current is sufficient. The power supply voltage is higher and the relative power will be larger. The speakers with different impedances will have different output power. In the case of sufficient voltage and current, the larger the ohms of the horn, the smaller the relative sound power. pay attention! Only the above package content, other products are not included. Note: Light 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.