I have about 15 of these on windows around the house and they are just slim enough to fit between the window and the screen of my Pella casement windows. I had to mount the magnet off at an angle, so it does not rest in perfect position when the window is closed, but it still works properly. The 6160RF keypad sets about 80' (line of sight)from the farthest 5820L and I had problem with just that one sensor not getting adequate connection, so I had to add a 5800RP (repeater) and bow everything is great. The 80' is going through drywall, ductwork, electrical, wood, etc - there is a lot of disturbance within that 80', so I was amazed it actually went that far.
Great units for casement windows, and big house with lots of obstructions.
Wanted to monitor my garage side door. Plugged batteries in, and followed the security panel instructions for adding the zone, and it worked without issues.