This 2 watt mono amplifier kit is based on the TBA820 8 pin DIP

3vDC = 200mW 4 ohm speaker
6vDC = 750mW 4 ohm speaker
9vDC = 1.6W 4 ohm speaker
12vDC = 2W 8 ohm speaker
S/N ratio : 80dB (A weighted)
frequency response : 20Hz to 20kHz (-3dB)

On board PCB trim pot style input level adjust.
Power supply can range anywhere from 3V - 12V DC.
The speaker shares a common ground connection.
Dimenions: 1 5/8 X 1 3/8 X 3/8"
(41 x 35 x 10mm)