I used a 500R for a month or so and finally bought a Ranco. If I had to do it over again, I would have just bought the Ranco or Johnson Controls right off the bat -- the 500R at $30 is a pile of crap. For $40 more, you can get a thermostat that actually holds its settings, is handmade out of high quality materials, and will work for basically forever. I bought mine from Reptile Basics, Inc (RBI), and was very pleased with the experience.
My 500R barely gets the UTH to 89 at MAX setting, and if the room temp drops any, it's over with.
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