This dew zapper is made to gently warm the miniscus lense on catadioptrics. This 5" one is made for the Starmax 127, but may also be used on other scopes of similar size. You could even add a little velcro on it and use it on something smaller like a 4" refractor. It has only been use a few times. I don't have the box anymore, and I don't think it came with any paperwork, but it's in close to new condition.