The IEI 834LWC Viper Plus with Contact is a frame mount glassbreak/ selective vibration detector that incorporates a normally closed window/ door contact. The Viper Plus contains a custom integrated circuit designed specifically to detect vibration signals associated with forced entry in a wide variety of surfaces including: windows, doors, walls and glass of all types. You can adjust the Viper Plus for sensitivity over a wide range, but it's immune to low frequency vibration. The Viper Plus is a standalone sensor with no additional processor required. The door/ window contact allows the Viper Plus to monitor the opening of a point of entry.