Features: White surface mount magnetic contact reed switch kit with pigtail for home metal door or window security alarm system. Normally closed type, when the switch and magnet is close to each other the switch is closed, otherwise it will be open. The reed switch is an electrical switch operated by an applied magnetic field. Designed for use with alarm systems. Great for use in family and factory window, door. etc. With double-sides tape design that for easily install. Note: No external power supply, connect to wired or wireless alarm control panel GND and N.C ports directly Please note that this item not fit to iron door, It will decline magnetic of the sensor. Specifications: Item Type: Door Sensor Magnetic Switch Material: ABS Model: MC-31 Color: White Size: 6.22cm/2.440.79in (Approx.) Actuation Distance: 16mm Rated current: 100mA Rated voltage: 100V DC Operating distance: more than 15mm, less than 25mm Rated power: 3W Connecting mode: NC. (normally closed) Quantity: 1 Set (other accessories demo in the picture is not included) Note: 1.Transition: 1cm=10mm=0.39inch 2.Please allow 0-1cm error due to manual measurement. pls 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 X MC-31 Wired Door Window Sensor (No retail package) 20 X Screw