There are several things that factor into the size of the RHP. Such as.. Cage size, cage material, High and low temps of the room that the cage is in, What type of animal is in the cage and even things like is the cage near a concrete floor. Heat tape is Used in the same way that UTH are used so they pose the same risk factors as UTH. The down side to RHP are that they are very pricey as compared to heat tape or the cheaper zoo med brand of UTH. They are comparable though to a high quality UTH such as a Kane brand UTH. DO yourself a favor and call Bob at pro Products. You do not have to buy his equipment but just take a few moments and ask him about his RHP and let him give you some very valuable info! I was sold after talking to him BUT even better yet.....I found that all his information was CORRECT![]()