Enhance your home security system using these magnetic contact security sensors to safeguard your home's doors and windows. Each of the 10 pairs of included Surface Mount Miniature Contact Switches are half the size of standard magnetic contacts, making them perfect for discretely hiding behind window and door frames. In addition to windows and doors, these small contacts are ideal for alarming safes, gun cabinets, jewelry boxes, china cabinets, or just about anything that opens and closes. This Miniature Magnetic Contact Switch is also available individually.Compatible with most standard, hardwired alarm systems. They stick on with supplied self-adhesive tape, or can be screwed down. These contacts work for normally closed applications, which means that they are considered 'closed' when magnet and sensor are aligned; i.e. doors and windows are typically in a closed state.