These are pretty good covers for the price. They just slip on the ends of the scope. As such, they are not a super-tight, permanent installation: they do move around a little due to recoil, however, this is not a big deal, you just push them back into position periodically. The cover on my eyepiece closes with a positive snap but the cover on the objective lens is harder to close positively: I have to fuss with it a little and push it pretty hard to get it to snap closed. I think this is just due to manufacturing in the plastic/rubber. Both covers snap open quickly & pretty quietly.