Let me start by saying this: the Honeywell Thermostat Guard isn't Fort Knox for your thermostat. If someone really wants to break in, they absolutely can - a hammer would make quick work of this plastic box. But here's the thing: that's not really what this product is for.
I installed this in my office where employees kept 'adjusting' the thermostat to arctic temperatures. The moment I put this guard up with its little lock, the problem stopped completely. There's something psychological about that locked clear box - it sends a clear 'hands off' message without being obnoxious.
The installation took me about 5 minutes - just four screws into the wall around my existing thermostat. The clear plastic is thick enough that it doesn't feel flimsy, and after six months of use, it hasn't yellowed at all like some cheaper plastics do.
Now for some real talk: the design could be better. When you unlock it, the front panel doesn't stay open - it completely detaches from its hinges. At first I thought I broke it! It's not broken, just poorly designed. You have to hold it open with one hand while adjusting with the other.
Size matters here - measure your thermostat carefully before buying. My round Honeywell fits fine with room to spare, but I've heard from others whose units were too large. The product dimensions are accurate though, so just check yours first.
For $15-20, this does exactly what I needed: keeps casual adjusters away from my thermostat without requiring major installation or looking like industrial equipment on my wall. It won't stop a determined vandal, but it absolutely stops curious fingers - whether they belong to coworkers, kids, or elderly relatives with temperature preferences.