OP/TECH USA Fastcap with Metal Ring - 49mm
Photographers agree that the OP/Tech 49mm Fast Cap is truly a winner. It is not only loss-proof, but it's dust-proof as well thanks to the integral semi-"O" ring seal. Once attached to a lens or filter, the base stays in place when the hinged, spring-loaded lid is flipped open by a flick of the thumb. The cover can be adjusted for the most convenient position of the opening tab. The Fast Cap is available in a universal design to fit most normal/telephoto and wide angle lenses. It's simply the best protection available.