Features: Brand new and high quality. Surface mount magnetic reed switch kit, white, wired for home security alarm systems on metal doors or windows. Normally closed: When the switch and magnet are close, the switch closes; otherwise, it opens. The reed switch is an electrical switch that is activated by a magnetic field. Designed for use with alarm systems. Ideal for windows, doors, etc., in homes and factories. Includes double-sided adhesive tape for easy installation. Note: No external power is required; connect directly to the GND and NC ports of the alarm control panel, whether wired or wireless. Please note that this item is not suitable for iron doors, as it will reduce the sensor's magnetization. Specifications: Item Type: Magnetic Door Sensor Switch. Material: ABS. Model: MC-31. Color: White. Size: 6.22 cm (approx.). Actuation Distance: 16 mm. Rated Current: 100 mA. Rated Voltage: 100 V DC. Operating distance: greater than 15 mm, less than 25 mm. Rated power: 3 W. Connection mode: NC (normally closed). Quantity: 1 set (other accessories shown in the picture are not included). Note: 1. Transition: 1 cm = 10 mm = 0.39 inch. 2. Please allow 0-1 cm error due to manual measurement. Please make sure you do not mind before you bid. 3. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package includes: 5 pairs of MC-31 wired door/window sensors (without retail packaging) and 20 screws.