The speaker for protection board using UPC1237 dedicated chip design and manufacturing,has a power-on delay and for DC for protection,instant shutdown feature,all-round for protection of your expensive speaker Sheet selection 1.6MM thick high-FR-4 board manufacturing tin foil sprayed,10A relay is loose music quality, the resistance rings are gold film resistor copper feet. And with a red power indicator,power relay approximately 3 seconds,indicating that green light,the work indicator. The for protection board using a single power supply voltage AC 10V-18V,for DC 12-24V,you can take a group of electric power to the amplifier board.Try to use conditional independence winding or separate power supply. Mute delay boot,shutdown speed off. Amplifier midpoint potential for protection,the midpoint of for DC from the control point of> 0.7V. All finished boards are good debugging,and power test. Size:6.5x5cm/2.56x1.97inch Note: Please allow 1-3mm error due to manual measurement. pls make sure you do not mind before you bid Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you Package Included: 1x for Protection Circuit Board