Using the digital power amplifier chip TPA3116D2 efficient D class operation Power amplifier chip has more than 90% power efficiency and low power consumption when standby. High-level modulation system configuration, highly integrated level reduces the quantity of components. Self-protection circuit includes over-voltage, under-voltage, overheating, DC detection and short circuit protection, heat-resistant package. Bluetooth transmission distance is about 10 meters, if used for a speaker, it is best not to use the Bluetooth signal shielding material. Specifications: Colour:blue Material:plastic Chip: TPA3116D2 Bluetooth: btm836 / csr8635 (4.0) Voltage: DC12V~24V Current: Greater than 3A Channel: Dual channel Output Power: 120Wx2 Efficiency Ratio: Greater than 90% Amplifier Size: 98*79*16mm / 3.85 inch * 3.11 inch * 0.63 inch Bluetooth Modulation Mode: GFSK/ 4 DQPSK, 8DPSK Voltage: 3.3V~4.2V Support Bluetooth Protocol: HFP V1.6, HSP V1.2, A2DP V1.2, AVRCP V1.4, DI V1.3 Operating Current: less than equal 30mA Standby Current: Less than 50uA Temperature: - 40 Degrees Celsius~ + 80 Degrees Celsius Max. Distance: 10M / 32.8ft Transmission Power: Support CLASS1 / CLASS2 / CLASS3 8dBm Max. Sensitivity: - 80dBm Less than 0.1%BER Frequency Range: 2.4GHz~2.480GHz External Interface: PIO, SPI, Audio Input/Output, PCM, USB Audio Support: AAC, MPA, SBC, stereo Distortion Factor: less than equal 0.1% Bluetooth Size: 21.9*14.1*1.8mm / 0.86 inch * 0.55 inch * 0.07 inch Package Includes:1 x Audio receiving digital amplifier board Note: Light shooting 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.