Vktech Remote Control Door Window Entry Alarm Burglar Alarm Anti-theft Detector For Homes, Apartments, Dorms, Offices, Hotel Rooms, Garages And More Compact design, no wiring required, electronic magnet sensor detects entry Easily mounted to door / window with attached double-side adhesive tape Send out loud voice to frighten the intruder and warn the master when alarm is activated Ideal entry warning for homes, apartments, dorms, offices, hotel rooms, garages and more Batteries: 2x AAA batteries for main unit (batteries not included)