Ultra Reliable Glass Break DetectionProtect your most vulnerable point of intrusion! Window Bugs use a patented tuning fork to detect glass breakage simply and reliably. It is not affected by normal shock or vibration, so you won't have to worry about false alarms. Dry Circuit No Power Required Peel and Stick Mounting Protects up to 32 square feet Automatic Reset HG Compliant - no mercury Factory default to Normally Open (can be adjusted to Normally Closed with select USP controllers) United Security – Robust, Rugged, ReadyUnited Security Products (USP) has supplied quality products to the security alarm industry for more than 40 years, with proven performance in more than 100 million installations. Security systems professionals rely on USP for the most innovative products in the security industry. For your next installation, be sure to specify USP products.