Cinematics Dslr Lens Gear Ring for Follow Focus Belt 70-80mm for Dslr Pro Mod 0.8 Black Universal follow focus Gear ring for DSLR lens focusing Size: internal diameter 70mm-80mm, external diameter 120mm; Thickness: 12mm; Net weight: 40g; Material: ABS plastic for durable use; Color: black; Gear mods: standard 0.8 mod This gear ring is for DSLR lens, focus ring diameter between 70mm~80mm, not lens filter size. If you cannot measure focus ring diameter, please measure focus ring perimeter, then divide  (3.1416) to get the diameter. Advantage: we have a set for 6 different sizes, from 60mm to 116mm, clients can choose according to the lens focus ring diameter, our gear rings have unified external diameter 120mm with standard 0.8 modulus gears, photographer doesnt need to change follow focus position for different lenses during shooting. Universal for all dslr lens which focus ring diameter is 70~80mm adjustable