This includes 7 phot r step down rings ranging from 49mm to 77mm step down rings also known as adaptor rings allow you to use filters and accessories that are not the same size as your cameras lens lenses and filters come in a large range of types and sizes and unfortunately they dont always fit together correctly fortunately there is a step down filter that you can use step up rings provide a way to fit a larger diameter filter or accessory onto a smaller lens the step down rings screw