ProPto(TM) Anodized Black 52-43MM Step-Down Adapter Ring Stepping Ring 52MM Lens to 43MM Filter Size for Camera Canon Nikon Lens Side : 52mm/ 2.05" Filter Side : 43mm/1.69" Material : Metal Anodized matte finish to compliment your camera Allows you to use larger size filters on lenses with a smaller diameter thread. The first number is the size that screws into the lense, the second number is the filter size.