It's possible the surface wasn't cleaned properly, or their climate is humid

Sticks well on smooth surfaces and does not have to be perfectly lined up to work.

Clean the surfaces and the adhesive really sticks.

They will stick to metal or wood with ease if you clean the surface properly

The alarm is very loud, so there's no worrying about not hearing it, and the sticky surface sticks to pretty much anything

I cleaned the surface very thorough and pressed the units on the door frame as hard as possible but about 2 weeks after installation they fell off

The only complaint I have is that they don't stick well; this surprised me because the adhesive seems strong enough and I made sure the surfaces were clean and dry.

That would not have bothered me if they worked as they were supposed to work

They have given me such a great sense of security, if even just to let you know there is a potential breech from an intruder to buy you time to act as well as

Couldn’t get them to work as

It works on our sliding doors and another door with a little bit of a gap, as they don’t alarm until they