Key Features Soft Plastic, Slip-On Design For Lenses with 115mm Outside Diameter Protects Lens Elements When Not in Use The 115mm Push-On Lens Cap from Schneider is a simple, soft plastic slip-on style cap designed to protect the front or rear elements of a lens when not in use. The cap fits lenses that have a front or rear ring with an outside diameter of 115mm; this size differs from the threaded filter ring diameter of a lens.