The Kenko KSUR Step-Up Rings allow a larger filter or other accessory to attach to a lens of a certain size. For example, a KSUR-5277 would allow a lens with a 52mm filter thread to mount a 77mm filter. A wide variety of lens-to-larger-filter or accessory combinations are available. The Kenko step up rings are made of lightweight aluminum alloy that is anodized in a black finish in order to be durable and resist corrosion.