If you don't have one, get one.. matter of fact, get two as a back up to your back up. Ha.. I recently bought a thermometer gun because I read about it on a thread here and thought it would be a good idea to double check the temperature the Accurite Thermometer/Humidity was giving me. Whoa!! How did I live (or how did my snakes live) without this thing? While the Accurite temps weren't extreme off for the spot the probe was sitting on, as I scanned the entire warm side, I noticed areas had higher temps... much higher temps. I discovered my warm side had hot spots. What the heck! I thought my BP was out because he was happy to see me ("Is that a hot spot in your hide or are you just happy to see me?".. LOL) Turns out he was a bit too hot.
I adjusted the heat mat but will likely buy new ones since these have some years to them. I got mine from ebay - http://www.ebay.com/itm/NON-CONTACT-...item1e7ef8347d
I'm not endorsing this seller or the site but this is where I got mine and its the cheapest I see online. Again, if you don't have one, get one. It also helps to check the temperature of the water when you are giving your BP a bath. And that's my testimony.