The HUSK-20 is a mechanical hold-up switch designed for silent operation. It is activated by using one finger to press down on the switch. When activated, the switch mechanism locks, insuring an immediate alarm signal. A status window designed on top of the hold-up switch indicates its condition: RED (alarmed) and BLUE (armed). To reset the HUSK-20, use the key provided. The housing is made of metal and is painted gray.The hold-up switch sends a signal to a dedicated 24 hour hold-up circuit of a burglar control panel. That signal in turn will send the immediate signal to police or central station.