4 in 1 mode: this alarm with 4 modes. 1. Time delay alarm (sounds 'Di-Di-Di' from 0dB to 108dB if the door remains open for 3/15/30/60s) 2. General alarm (alarm stops if door closed); 3. Constant alarm (constant alarm even closed door); 4. Door Open Chime (Sounds DingDong once the door is opened) 108 dB Loud Alarm: The door and window alarm helps effectively deter intruders/thieves with a loud alarm of 108 dB. You can easily set the appropriate mode according to your needs. Easy to install: Simple peel and stick installation, easy to install on most freezers/refrigerators or any door without any tools. package including 2 refrigerator alarms, 2 magnetic strips, double-sided sticker, user manual. Installation note: Be sure to close the alarm and magnetic strip, distance installation distance between them should not exceed 0.78 inch. The 2 pieces must be aligned by their alignment arrow. 2 AA batteries can last 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, swimming pool sliding door, store, office, apartment, hotel, etc. Multi-purpose: 1. Refrigerator, Fridge, Freezer Door Alarm Reminder 2. Window door alarm for home security 3. Cabinet door alarm in store security Package including: 2 x refrigerator alarms 2 x magnetic track 2 x double-sided sticker 1 x user manual Battery operated, it requires two AAA alkaline batteries (not included). It's a physical image. When the batteries are installed, the light will glow red. Low consumption design: Low consumption design, they can work for more than 2 years. Low battery warning, when batteries need to be replaced, the LED light flashes once per second.