"I bought this product in my local store. The outside of the box very clearly states that it is for certain gallon aquariums and that the length is 36". Upon getting it home and trying it out, it was only 35". I looked at the information inside and it said that it fits on the inside lip of a 36" tank. That's fine and dandy, if all tanks throughout history were manufactured by the same company and with the same design. Guess what...they're not. My tank, being a bit older, does not have the inner lip. Perhaps the company might want to put that information on the outside of the box in the future instead of assuming that their product is one size fits all."