works well. I like the sensitivity setting.

I wanted to put sensor on wall frame of window but it wouldn't work there. Had to put it on window instead.

Unit seems to work very well, I use them as shock sensors on the windows. The only reason I do not give it 5 start is because if you need to take the velcro glued side off to move it it no longers glues at all, seems to be a one time use only. Easy to install, however one of 8 units came with a dead 9v battery.