The door alarm emits a 120 dB sound, and the LED light activates when a door or window is opened more than 1 cm. This Noopel alarm system for home security is designed to quickly deter intruders and alert residents. Prevent children going out the house without notice.Also ideal entry warning for your home, office, apartment, garage and so on. Ultra-thin door and window alarm with 2 adjustable settings (off/on).3xLR44 batteries included. Easy installation, No wiring needed! No screws needed! Just affix the provided stickers to various parts of the house, such as doors, windows, cabinets, drawers and gates. (Note: Keep the installation area clean and ensure that the sensor is installed within 1 cm from the arrow side of the burglar alarm.) Ultra-sensitive also Low battery indicator to check battery life.This is a PERFECT AFFORDABLE compliment for your home security. Prior to purchase, please verify that the door or window frame provides sufficient space to accommodate the magnetic sensor, with a minimum width of 0.5 inches.