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 compatible with 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" once door is opened) Loud 108dB Alarm: The 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/refrigerator or any door without any tools. package including 2 fridge alarms, 2 magnetic strips, double-sided sticker, user manual. The electronic instruction is on the eighth picture. Installation Note: Be sure to close the alarm and the magnetic strip, the installation distance between them should not exceed 0.78 inch. The 2 parts must be aligned by their alignment arrow. Widely used: magnetic trigger door alarm sensor protecting home by door window entrance and suitable compatible with safe, cabinet, freezers, refrigerators, sliding pool door, store, office, apartment, hotel , etc.