Tronixpro 55mm Pro Series Snap On Lens Cap For Sigma Normal 50mm f/2.8 EX DG Macro Autofocus Lens This lens cap protects lens surface from dust & shock during storage. Unique snap on design allows easy installation onto the lens & one-step removal from the lens. It fits directly onto the lens with a double-action spring design. Microfiber Cloth 55mm Snap On Lens Cap