4 in 1 Mode: This alarm with 4 modes. 1. Timing alarm (sounds 'Di-Di-Di' from 0dB to 108dB if the door remains open for 3/15/30/60s) 2. General alarm (alarm stop if door closed); 3. Constant alarm (constant alarm even door closed); 4. Door opening chime (sounds DingDong when door is opened) Loud 108dB alarm: Door and window alarm helps effectively deter intruders/thieves with a loud 108dB alarm . You can easily set the suitable mode according to your needs. Easy to Install: Simple peel and stick installation, easy to install on most freezer/fridge or any door without any tools. package including 2 fridge alarms, 2 magnetic strips, double-sided sticker, user manual. Installation note: be sure to close the alarm and the magnetic strip, the installation distance between them does not should not exceed 0.78 inch. The 2 parts must be aligned by their alignment arrow. 2 AA batteries can stay for 2 years. (batteries are not included) Widely Used: Magnetic Trigger Door Alarm Sensor Protecting Home Through Door Window Entrance and Suitable for Safe, Cabinet, Freezers, Refrigerators, Door pool slider, shop, office, apartment, hotel, etc.