*A Door Watcher:Hang it on door knob or handle. When there is vibration ,it will make 115DB sounds. | *Static detecting:This function is available only when the door handle is made by metal. When someone is going to open the door and has not touched the handle yet. The alarm can sense the static electricity carried by human beings and beeps. | *Chime mode: to remind you someone has get in/out in a friendly way.If there is a toddler at home, use this to provent them from leaving alone. | *Small and portable:Idea for front doors, apartments, hotels, bedrooms, dorm rooms. Take the alarm with you when traveling, it is your door watcher your safety guardian and your travelling company.Set in 2seconds: Placei -> open -> go to sleep | *Three AAA batteries needed: (they are not included. Customers need to purchase separately.) The three AAA batteries can last approximately 1500 hours in standby mode. The alarm beeps for change while low batteries.