I put them on one of my scopes and to get it on right took some "thinking" to do it right due to clearance if memory serves me right, never had a problem with them since.
Brian, it's funny you mention that because I have actually taken my scope off to get the caps on. It wasn't until my second set where I realized that the inside threads actually spin independent of the cap housing and you don't have to remove the scope. Man I felt pretty stupid after that In my defense though, I don't think they put any directions in the package, not that I would have read them....
I put them on every Leupold scope I use. They are great at keeping both dust and water out. They aren't water tight or dust proof, but it will definitely be a thousand times better than if you have nothing on it at all.
Dack...you are correct it took me few minutes to look over the problem then figured it like you said, the inside threads were free to rotate.
Cost more that regular ones but like you said, never have problems with since.
Thanks to everyone who replied. I have since bought a pair of them for my scope, installed them, and have had one weekend hunt with them. So far, so good. I think I need to do a better job tightening them up so they stay in place.