1. The DC protection can't work with the Digital Amplifier board or BTL Circuits 2. The horn protection board has the functions of -on delay (about 3 seconds) and DC protection (control voltage is about 1V). The board circuit is simple and safe and reliable. 3. With LED light indication, it lights up when working, and it is extinguished when protection starts. It adopts double parallel relay, which is suitable for amplifier boards. 4. This protection board is powered by AC 12-18V.It must be powered by a separate supply. Otherwise, the amplifier board may be . Can withstand : 50W-300W Protection board size: 68 x 55 MM Maximum Per Channel: 101-130W Number: UPC1237 Channels: 2 (2.0) Type: Home Amplifier color:Photo color Material:ABS Package Contents: 1 x Speaker Protection Board Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.