PROMASTER®  77MM PROFESSIONAL SNAP-ON LENS CAP #4585 The Professional Lens Cap is MORE than your everyday lens cap. PROMASTER Lens Caps are precision molded for optimum fit and use a center activated locking system that aids in the secure fit of the cap. The PROMASTER Professional Lens Cap is the ideal replacement cap for your valuable lens. Available in all popular sizes. COMPATIBILITY 77mm threaded lenses