TPMS

I took the security covers off our 10 TST standard 507 sensors a couple of years ago, and haven't lost one yet. I think they're small enough without the caps that they probably go pretty much unnoticed, and just look like slightly large standard valve caps. Ours are on and in use year round so they only come off for battery changes or airing up, but the batteries still usually last close to two years. I install the sensors with a dab of dielectric grease on the threads to minimize any corrosion issues.