4 in 1 Mode: This alarm has 4 modes. 1. Timing alarm (if the door is kept open for 3/15/30/60 seconds, 'Di-Di-Di' sound from 0dB to 108dB) 2. General alarm (if the door is closed, the alarm stops); 3. Continuous alarm ( 108dB loud alarm: Door and windowalarms help effectively deter intruders/thieves with 108dB loud alarms. You can easily set a suitable mode according to your needs. EASY INSTALLATION: Simple peel and stick installation, easily installs on most freezers/refrigerators or any door withoutany tools. Package includes 2 Refrigerator Alarms, 2 Magnetic Strips, Sided Sticker, User Manual. Electronic instructions are on the eighth picture. Installation Precautions: Be sure to turn off the alarm and the magnetic strip, and the installationdistance between them cannot exceed 0.78 inches. The 2 parts must be aligned by their alignment arrows. 2 years on 2 AA batteries. (Battery not included) Widely used: Magnetic trigger door alarm sensor protects home through door and window entrance,suitable for safes, cabinets, freezers, refrigerators, swimming pool sliding doors, shops, offices, apartments, hotels, etc.