"After reading the previous review i was a little dubious about this product. Previous sensors lasted 22 years. New product easy to fit and change over existing 6 wire system, quickly picked up movement within two minutes. The sensor is fitted high on an internal wall in the living room which is 23 feet long, it is positioned directly towards a door and large bay window. It picks up entry into the room and movement within the room, but does not pick up movement outside of the window. Final adjustment of the sensors was carried out after the front of the sensor was fitted and screwed to the wall Fitted two months ago, no problems so far."