The Olympus LC-46 Lens Cap for Select M.Zuiko Lenses is a replacement for the front lens cap supplied with the lens--it protects the front element when the lens is not in use.
Fits M.Zuiko ED 12mm f/2.0 lens, M.Zuiko Digital ED 60mm f/2.8 Macro lens, M.Zuiko Digital 17mm f/1.8 lens, M.Zuiko Digital 25mm f/1.8 lens and other lenses with a 46mm front diameter