TPA3255 Amplifier Board 600W Single 300W Dual Sound Channel Modes Adjustable Multiple Protections Design Compatible with 18-50VDC Power Source Name: Amplifier Board  Material: printed circuit board Adaptable powersupply: 18-50VDC, limit 53V. recommended e direct current powersupply with voltage 36-48V and current 10A or above. The higher the voltage, the higher the output power. Applicable speakers: 3-8 ohms in BTL dual-channel mode, 50-300W; 2-8 ohms in PBTL mono mode, 100-600W Cooling mode: temperature-controlled automatic air-cooling or manually selecting the fan to keep turning Gain selection: potentiometer 10-gear adjustment, 26dB-36dB Bridging mode: power off first, 1 dip switch to ON position, output R+L+ shorted parallel output, R-L- shorted parallel output Maximum power: BTL mode, 2*300W@50V 4Ω, 160W@50V 8Ω; PBTL mode, 600W@50V 20, 300W@50V 40,160W@50V 8Ω Item size: 125 * 65 * 38mm / 4.92 * 2.56 * 1.50in Item weight: 254g / 8.96ounce Package size: 155 * 95 * 50mm / 6.10 * 3.94 * 1.97in Package weight: 289g / 10.19ounce