Universal follow focus Gear ring for DSLR lens, a set 6pcs different size, each can be adjusted about 10mmSize: internal diameter 60mm-70mm; 70mm-80mm; 80-90mm; 90-99mm; 99-108mm; 108-116mmexternal diameter 120mmThickness: 12mmNet weight: 40g/pcsMaterial: ABS plastic for durable useColor: blackGear mod: standard 0.8 modPackage includes:1 x 60mm-70mm Gear ring1 x 70mm-80mm Gear ring1 x 80mm-90mm Gear ring 1 x 90mm-99mm Gear ring1 x 99mm-108mm Gear ring1 x 108mm-116mm Gear ring 12 x screws ( 30mm 6pcs and 50mm 6pcs)1 x 4mm Allen keyThis gear ring set are for DSLR lenses, focus ring diameter between 60mm~116mm, 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.Advantage: clients can choose different size gear ring according to the lens focus ring diameter, our gear rings have unified external diameter 120mm with standard 0.8 modulus gears, photographer doesn’t need to change follow focus position for different lenses during shooting.