DITOP&reg; Mini Wireless Door & Window Contact Alarm & Chime Set of 6 , Batteries Included , Louder than 90dB , Mounted By Double Adhesive Tape Inconspicuous and Wireless, Easily mounted by double adhesive tape to window or door, no tools required. Residential use: Protects exterior door, sliding glass door, gun and medicine cabinets. Commercial use: Protects showcases and cash registers High Quality Intrusion Alarm, Louder than 90 dB alarm scare off potential intruders . Operated by three 1.5VLR44 button cell batteries(Included) , On and Off Switch Magnetic sensor switch detects entry protecting you home or office whether you're in or out. Chime or alarm mode.