Material: ABS Quality Item Type: Door contact sensor Installation: Peel off the double-sided tape, then stick 2 pieces on the door or window. align the small triangle and keep a distance less than 1 cm 4 steps to pair the contact sensor with the receiver: 1) Charge the batteries for the receiver if not, hold the contact sensor close to the magnetic bar. 2) Press the "Power/Mode" key on the receiver for 3 seconds to turn it off . 3) Press "volume key" for 3 seconds, the receiver will enter learning mode 4) Separate 2 parts of the contact sensor, the indicator of the contact sensor will flash once, which means pairing successful. Parameter: Material: ABS plastic Battery: 1 * AAA battery (not included) Contact sensor size: 79*30*15mm Magnetic bar size: 40*12*12mm White color Quantity sold: 1 piece Standby current: <40uA Working current: < 100 mA Working environment temperature: -10~+60oC Working environment humidity: < 90% Storage temperature: -20oC~+60oC