Sunrise Adjustable Follow Focus Gear Ring for DSLR Lens, 3 Pieces Suitable for Lens Sizes Between: 180-220mm, 211-250mm, 241-280mm Professional and apply to most of the DSLR lens Convenient and adjustable Make focusing more exact I set includes 3 pieces of gear rings Suitable for the lens during below sizes: 180mm-220mm Size A, 211mm-250mm Size B ,241mm-280mm Size C