CG512A1009 Large Thermostat Guard, Fits Thermostats 8. 25" W x 5. 75" H or Smaller

Nice and big and it should get the job done! I'm so sick of coming home to find the A/C turned off because the 70 year old man is cold in 80 degrees.

Keep people from changing the thermostat in my home. It was easy to install and comes with two keys

No longer fighting with the family on the settings.

These are great covers. I ordered 4 of them (3 medium and 1 large) and they all came with the same key. This is convenient; but I'm not sure it was intentional, or if all these covers just universally have the same key. Anyway, they're easy to install and they look nice. My only complaint is that the two pieces fit together SLIGHTLY loose, meaning there's just a little bit of play between them when it's locked. This doesn't create a bit issue, but it would be nicer if they were a snug fit, which I think would discourage tampering. The plastic is durable, though I will say that the reason I purchased these was to replace some that had been tampered with and were broken, so the plastic certainly isn't break-proof. If you're looking for something to prevent access, you may want to look at a metal option or something stronger. If you're just looking for something to discourage people from trying to tamper with the thermostat, this is a good, affordable option.

It’s perfect when you’re having rooms for rent and you don’t want people messing with the thermostat

worked until daughter hit it with hammer

Too big

I purchased this to use at my jobsite. Not to protect a thermostat, but to protect the sensor box that controls our double automatic sliding glass entry door. Even though it's about 8 feet off the ground, someone jumped up, took a tool and hit the bottom where the key mechanism is, which broke the acrylic, allowing anyone tall enough or standing on something the ability to stick their fingers in where the chunk of acrylic was broken out, enabling them to maneuver the settings. With the switch in the wrong position, my apartment building residents were put at risk because some smart-aleck would occasionally place the switch in a position allowing the door to open just by sensing someone approaching it, like at a grocery store or other businesses with sliding doors. You don't want that at an apartment building which requires the residents to let their visitors in after their presence is announced at the call box.The previous guard was the medium sized and was installed with the key in the down position as in the product description photo. I had the new one installed key on top instead. I believe that makes this stronger and less resistant to a hit. So far it has worked out very well and is very sturdy.