I originally bought this thermostat temperature reading laser gun to keep an eye on what the temperature is going into the supply and coming out of the return because Summer is here and I want to make sure that my air conditioner is running efficiently in the way that it should be and performing my due diligence even though I'm not an HVAC technician I know how to do basic things and I know a little about a lot of things, so I cleaned the coils on my outside unit because they were absolutely filthy after going through the very windy winter months and every year about this time I take off the cover to expose the coils and I gently and carefully with a hose using my thumb as the sprayer clean each layer very slowly and carefully without damaging the coils and removing as much dirt as I possibly can and I usually take about an hour and a half to two hours doing that to make sure that I have cleaned it as good as I possibly can so that way I know it will have no problem sucking in air and it won't be struggling to do so and also checking my filter which I use the cheap filters so that way there are no air restrictions instead of the pleated cloth filters which causes more problems than most people realize, I use the cheap fiberglass filters which do exactly the same thing except they allow for easy air flow which is exactly what you want and then I check my evaporator to make sure that was clean and I just had to clean that off a little bit and maybe the only thing I have it done is taking a vacuum and stuck it inside of each register to clean whatever little bit of junk gets in there every now and then but I'm not too worried about that because there's never really anything in there, I don't have kids so there's no one to throw toys or trash or whatever in there and I also got myself a brand new thermostat because I believe my other one was on the fritz and it was giving me questionable temperature readings and my unit seem to be running longer than it should be and not cutting off when it should be so I did away with the seven day programmable bullcrap thermostat and got a simple single stage non-programmable thermostat with a cool off and heat button and that's that with a big digital display and a bright light up screen in the background and I've had that for about a week so I have been monitoring that quite often on a daily basis as well as making sure the temperatures are where they should be as far as going into the return and coming out of the supply and I have my thermostat set right around 68° and using this thermostat gun after letting my air conditioner run for a good 20 to 25 minutes to get a consistent temperature I then start measuring the temperature of the air coming out of each event which should be anywhere between a 15° and 20° difference than the temperature I have my thermometer set at and right now I have it set at 67° and as you can see by the picture I posted after I just took the temperature coming out of my vent in the kitchen it read 51° which is exactly right around where I want it and I went around to each vent in my house and check the temperature from each one and I have a basement so of course it's going to very because it's cooler in the basement so it rained anywhere from 48° to 52° and it just gives me more confirmation and knowing that my air conditioning unit is running efficiently and working as it should be and these are all simple things that any homeowner can do if they think that they're having any kind of issues, check the easy things first at any homeowner can check before freaking out and calling an AC repairman to come over and spending a whole lot of money that you didn't need to spend which usually happens 9 times out of 10... As far as I can tell this thermostat gun is about as accurate as I would expect it to be, I can't say that it's 100% accurate but I don't think I would be able to say that about any different kind of thermostat, but I tested it on several different things and it is about as close as I needed to be so I would definitely recommend this product