Universal follow focus Gear ring for DSLR lens focusing Size: internal diameter 60mm-70mm, external diameter 120mm; Thickness: 12mm; Net weight: 40g; Material: ABS plastic; Color: black; Gear mods: standard 0.8 mod This gear ring is for DSLR lens, focus ring diameter between 60mm~70mm, not lens filter size. If you cannot measure focus ring diameter, please measure focus ring perimeter, then divide π (3.1416) to get the diameter. We also accept Customize smaller size, if your lens focus diameter is smaller than 60mm, please let us know, we will send 2pcs of rubber strips, which can be cut into pieces and pasted inside the ring.