Losing a client's keys, in the commercial janitorial service industry, is a nightmare. Particularly if, like we do at CBN, one stresses tight security in serving clients.
The issue, of course, is the unintended (or sometimes intended) separating the cleaner from the keys. The clip to your belt may break; or you may put the keys down, say on the front desk, after locking yourself into the building, and forget where you put them; or have them in your hand (you think) as you take out the trash. Or you carefully set them on the front desk, went out the back door to take out the trash, and the door swung shut and locked behind you (and you likely left your cell phone on the desk with the keys...).
Hate it when that happens.
Imagine how nice it be to have a system where, when you take the keys off the (relatively unbreakable) belt clip, the keys and tje belt clip holler at you, and flash a light, and maybe even vibrate, if they sense more than a few feet of separation, or for a duration of more than a few seconds.
Found one. It's called a Gravity Key Tether by Tether Technologies. Try it out.