With the new original TDA8954TH , the BTL bridge circuit is more efficient. Adopt original original rectifier bridge, original J13003 transistor Adopt 2200uf array capacity electrolytic capacitor. Kernel chip: TDA8954TH Input : recommended dual 24V toroidal transformer (range dual 12-double 18V) Output : 420W Number of channels: mono Output impedance: 2-8 Ohm (4 Ohm recommended) Size: 82 * 72 * 37mm colour: black Material: metal Net weight: about 121g Package Contents: 1* 420W TDA8954TH Digital Audio Amplifier Board 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.