The Honeywell Ademco 4959SN V-Plex is an addressable Form A SPST overhead contact with a rating of 100ma at 28VDC. Equipped with Honeywells patented polling loop technology, an epoxy-seal, and waterproof aluminum body, this contact is ideal for commercial or industial settings with more rugged conditions. Completely programmable from Honeywells VISTA series keypads. Perfect for installation on heavy swinging doors or windows. Also known as -Honeywell Sensors SERIAL # MPX OHD CONTACT - 4959SN