Just got my Temp Gun today - TG1. After measuring everything from the interior of my car in the sun (Dash was at 161 degrees), to my iced tea in my cup (tea at 41, ice at 27), I proceeded to check out my enclosures. My Herpstats are set at 86 degrees, with the probes attached at the back of the 11" strips with electrical tape. I knew there would be some discrepancy since the probe is still in open air. But I was a bit surprised at what I found. * The Flex itself measured anywhere from 96 to 102, depending on which shelf I measured it on. * The floor of the tubs themselves, over the Flex, were anywhere from 89 to 96 - the tub floors do not sit directly on the Flex - they have a slight bow in them. * On top of the substrate, the temps on the hot side were between 75 and 82. On the cool side, the top of the substrate was pretty consistent at 74 to 76. So, while the temps are spot on for thermo-regulating, it was surprising to see the difference in temps with the same Flex on each shelf. Granted, 4 to 6 degrees isn't THAT big a deal with Colubrids, if I were keeping something more fragile I might try to change up the probe, maybe place it inside one of the tubs or totally encase it over the Flex.