Product Name: Magnetic Door Switch. Some installation parts; Normally Closed: The magnet is almost conductive, and the magnet is open when exiting. This is a set of magnetic detection switches used to protect doors and windows for the most part. A protective device monitors the opening and closing of doors and windows. Each Size (L x W x H): Approx. 106 x 38 x 10 mm / 4.2 x 1.5 x 0.4 inches; Detection Distance: 30 mm. The wired part is often installed on the fixed door frame, and the mating part is mounted at the corresponding position on the door. Easy to install and use. A good replacement for old contacts. Simple to install without hassle. High-quality magnetic sensor contacts with strong magnetic response, sensitive and long durability. Quantity delivered: 1 piece becomeveryrich