Equipped with an intuitive LED indicator (constant on during protection mode) and works with AC 12-18V Reliable direct current protection (1V trigger) and 3 second startup delay to protect your hearing equipment from surges in voltage Maintains seamless operation on most amplifier circuits Ideal for audio files, speaker builders, and professional technicians requiring safe voltage regulation of power amplifier boards This 2.0 speaker protection board features UPC1237 chip with double relay design