Window sensors

[mikefamig]

I have looked at window sensors in a numer of shapes and sizes and found these Honeywell sensors:
 
http://www.security.honeywell.com/hsc/products/intruder-detection-systems/sensor/contact/recess-mount/25392.html
 
My question is why would anyone want to drill a 3/8" hole 3/4" long in a window frame when these are available? I have found that the 1/8" thick magnet can be attached to the window frame and fits between the window frame and window sill without drilling the window frame at all if you flush mount the sensor in the sill.
 
Am I missing something? Is there a downside to these switches that I am missing?
 
Mike.

 

[RAL]

I don't think you're missing anything.  The switch contacts aren't any different, just the magnets.  The only downside to the rare-earth type disc magnets that I can think of is that they cost a bit more. 
 
Depending on the particular magnets you are comparing, there may be a difference in the gap distance.  Rare-earth magnets are typically stronger than a non-rare-earth bar magnet, allowing for a larger gap.

 

[Del91574]

Because on some windows, the option to have a 1/8 or so "washer" on the bottom of the sash is not an option and it'll cause the window to not sit square in the opening or close properly. Sure, you can recess the rare earth magnet, however the magnet isn't a "finished" material, has a screw to mount and both can start rusting.
 
Also...a rare earth magnet may be a slight press fit, but any sort of ferrous material nearby can cause it to pull out through the screw and any sort of press fit that was done is wood.
 
Also, if you have openings that tend to slam, rare earth magnets tend to turn into a very attractive magnetic dust.