Roller Ball Contacts Open Circuit On - Our Roller Ball Alarm Switch provides versatile security solutions.Roller Ball Contacts Open Circuit On features include: Suitable for security amp; alarm systems, signaling circuits and all types of general low voltage switching applications Used with Doors, Windows or Bell/Buzzer Alarm switch is designed to operate when depressed from any angle Low Voltage Only - 48V AC Max. 2 Nickel wood screws included Door Closed - Circuit Off (light off) Door Open - Circuit On (light on) Order Qty of 1 = 1 Piece Below is more info on our Roller Ball Contacts Open Circuit On