i have some real qualms about the Zoo-Med UTH's, and ANY UTH's widely available in pet stores. Here's an email exchange i had with Zoo-Med:

Hi there,

I am just emailing as a concerned customer. Regarding your Repti-therm Under Tank Heaters, I use them to heat both of my corn snake tanks, as well as my leopard geckos tank. Both the corn snake tanks are regulated using a Herpstat. I'm not sure if you're familiar with that product, but it is a proportional thermostat, which regulates the temperature of the UTH within approximately 1 degree. With my leopard gecko's UTH, i regulate it with a Zoo Med Repti-Temp 500R, which, as you know, is an on/off thermostat. Obviously it's not as accurate as a proportional thermostat, but it still does the job quite fine, i must say, at a reasonable price, compared to the Herpstat Proportional Thermostat, which cost upwards of $100 Canadian. Now onto the concern, i bought the biggest UTH to use with one of my snakes, and realized later that it was much too big, and i had to buy a smaller one. No big deal, i figured i would find a use for it somewhere down the line, which i did. When my boyfriend and I's first clutch of corn snake eggs began hatching, we were waiting on a shipment of flexwatt. We didn't have an alternative heating method for the new hatchlings, but i DID have the large Zoo Med UTH. SO i plugged it in, and waited about an hour. I came back from the grocery store, only to find that the UTH was over 100 degrees Fahrenheit, and the plastic was wavy and melted. MUCH hotter than ANY animal would ever require. In fact, it would BURN any animal that were to lay on glass heated with a Zoo Med UTH. So, i'm pretty disappointed that these heat mats are virtually unusable without being regulated.

Here's a quesion for you guys; howcome you don't make the UTH's with the Repti-Temp 500R's BUILT IN to them, and charge a higher price, or better yet, include a Rheostat (dimmer switch) that is pre-wired into the UTH? Because as we all know, they can get much too hot for any of our beloved pets. And as we also know, a lot of the people who we sell these beloved animals to, are (how shall i put it...) lacking smarts to actually BE a responsible pet owner, who a) does research BEFORE HAND about the animal they may purchase b) doesn't buy an animal (who, may live many, many years) on a whim, or a sense that if they own such an animal, it will make them "cool and c) practices proper husbandry to actually give these animals the enclose that they need to live properly. Basically what i'm saying, is we DO carry these UTH's in my store, but, i would feel much more secure about carrying and selling your product if you made it "fool proof," so to speak. Because i DO like the UTH's when regulated with a proper thermostat, but unfortunatley most people are not willing to fork out that amount of money, nor are they willing to go to the hardware store, fork out $7 for a dimming switch, and then turn on their computer, load up an internet browser, and google how to DIY wire a dimming switch.

So please, pretty please, for the love of our animals...could you PLEASE include a built-in rheostat in future models of your Zoo-Med Repti-Therm Under Tank Heaters?

Thanks for your time and consideration,
Katia *******

and here is their response:

Dear Katia,

Thank you for contacting us. I will forward your message to our product development team for their consideration. I do want to warn you however about using the under tank heater while it is not attached to a glass terrarium. This heater is designed to distribute heat through glass. If it is not attached to glass, the temperature reading you get is most likely not accurate as the heat is not being transferred away from the heater properly. The normal operating temperature of the heater is between 95 and 105 degrees but this usually produces a 2 – 10 degree temperature increase inside of a tank. We often recommend that the heater be used with a thermostat or rheostat for many applications, but in many applications these temperature controlling devices are unnecessary because of the low wattage of the heater. I would like to thank you for your time and your input and I will pass your concerns along. Please let me know if you have any further questions or concerns.

Kind Regards,

A***** **********
Customer Service
Zoo Med Labs, Inc.
3650 Sacramento Dr.
San Luis Obispo CA 93401
Toll Free 888-496-6633
Fax 805-542-9295

i like how, in the bolded section of the response, it clearly says "We often recommend that the heater be used with a thermostat or rheostat for many applications" yet NOWHERE in the instructions of a brand new Zoo Med UTH does it even make MENTION of a heat regulating device.

I GIVE UP!