Feature: Working principle of induction door magnetic: When someone opens a door or window (the host is separated from the magnetic strip), the door magnetic alarm immediately emits a loud alarm sound. Closed state: No alarm will sound when the distance between the host and the magnetic strip is within 1cm. Open state: When the distance between the host and the magnetic strip is more than 1cm, a loud alarm sound will be emitted. Five modes: - Door opening alarm, door closing stops - Ding-Ding doorbell mode - Door opening alarm for 30 seconds - DI DI DI mode - After 15 seconds of opening the door, the alarm will sound for 30 seconds before it ends (Short press to switch modes; Volume can be adjusted) Specification: Size: 6.5 x 3.4 x 1.65cm Package Included: 1 x Alarm Note: 1. Due to differences in monitors and lighting effects, the actual color of the item may vary slightly from the images shown. Thank you! 2. Please allow 1-3cm measurement deviation due to manual measurement. (1 inch = 2.54 cm)