120 LOUD ALARM – this Magnetic sensor window door alarm loud enough to detects entry, prevent kids and babies going out the house, protecting your home or office whether you are in or out. (audible up to 750 feet/230M away)EASY INSTALLATION - Easily mounted by adhesive, tape it on the window or door then all is done! No wiring needed! No screws needed! Completely DIY! (NOTICE: MAKE SURE THE GAP BETWEEN THE ALARM AND MAGNET PART WITHIN 1 CM.)ULTRA-SLIM DESIGN - Size: 2.9" x 1.5" x 0.4, ultra-slim door and window alarm with 2 adjustable settings (on/off). Perfect for home, office, garage, dorm room, apartment or even RV.LOW BATTERY INDICATOR – you will easily know when to replace the batteries with its low battery indicator, no worry about failing to work. ( 3xLR44 batteries included per alarm )