Jumbolo things found on MH

[James-Alex]

Hey folks full of knowledge!!
Can anyone identify these things? I’ve spotted them in a few places on are van and have no clue at all what they are. Inside has circuit type board and a battery like you would put in a watch. Mainly fitted on the doors.
Cheers

 

[ceejayt]

Alarm?

 

[pappajohn]

Cheap and nasty motion sensors.
If they work they probably screach when activated.

 

[James-Alex]

Tbh I’m not sure what purpose they serve. They’re on main hab door and garage door on one side. But if everytime I opened the door they went off id be so annoyed. Thankfully the battery gone and no longer work!