1.5V 1 PCS AAA battery.(not included) HOW TO INSTALL: 2.place the cover in place. 3.peel the paking of the alarm unit and place it on the edage of the moveable portion of the ON/OFF switch side away from the edge. 4.peel the backing of the magnetic sensor and place it on the edge of the oppsite side next to the alarm unit. Please check its sensitivity monthly, to make sure it is in good condition. Change batteries every 3-6 month. Specifications: Warehouse roll up doors Inside display cabinets Restricted area protection patio, bedroom, bathroom) window alert Home Security Mr. Mike Zhen
