Sensor antenna extension - Gun safe

I tried Aqara too and it never stayed connected in the safe. The Centralite I posted link to above is the same sensor @johnconstantelo posted. They were available on Amazon within the last year but no longer try directly on their website.

Another option which I have also used is @iharyadi Environmental Sensor though not sure he has any available:

Nice with it is you have other inputs to use as a contact sensor too all in one device.