Double type alarm sounds when glass is detected or impacts or when window is opened. The impact detection type detects glass breakage and shocks, so you dont have to worry about the accidental operation caused by the elements or vibrations caused by window opening and closing. When it detects impact or glass breakage, the loud alarm (approx. 90dB/50cm) will continue to ring for about 25 seconds. The main unit is only 0.3 inches (8 mm) thick, so it does not interfere with opening and closing of most windows. Large easy to operate slide switch to see during and unalerts at a glance. Can also be mounted on plate glass (uneven glass). Note: May not be able to install some decorative glass with large uneven surfaces. By adopting a newly developed original IC, it does not respond to vibrations such as rain and wind and windows and is achieved a precision impact detection system that only responds to the impact of broken glass.