Tork Door/Window Contacts, Rolling Ball Type APPLICATIONS: For unlocking or locking metal or wooden doors using low voltage wiring. For AC, use TA591 or TA592 transformer. FEATURES: Signals automatically with the opening and closing of doors, windows and transoms. Operates from pressure in any direction. Non-tilt, non-jamming design. Fits 3/4" hole- no need to mortise. DESCRIPTION: Momentary contact, Push to make & break