This item is used to step up a lens filter size of 55mm to 77mm and creates an 80mm outer diameter (O.D.) for uniformity of accessories across all lenses in your set.  Ring is made of solid billet aluminum and anodized black. Cap is made of injection-molded rubber.  Simmod products are extremely high quality.  This sale includes the front ring, black slip-on cap, and the clear plastic pouch.