Accessories such as a stepping ring are designed to attach different filter sizes to a lens. Often used to have a single filter and can install it on several lenses using a stepping ring. They are available in small to larger diameter versions "Step-Up Ring" (67 mm to 77 mm) or "Step-Down Ring" (77 mm to 67 mm). Be careful with a stepping ring, it can create an unwanted vignetting effect when installing a smaller filter than the diameter designed for the lens.