This is a Lens Focus Gear SIZE B.

For those of you shooting video with a follow focus, we carry these lens gears made by Redrock micro. They feature an industry-standard film pitch (0.8 mod 32).

Size A: lens diameter of 57.3mm – 70mm (2.25" – 2.7")
Size B: lens diameter of 67.1mm – 79.5mm (2.64" – 3.1")
Size C: lens diameter of 76.7mm – 89.1mm (3" – 3.5")
Size D: lens diameter of 89.1mm – 101.8mm (3.5" – 4")

Lens / Gear Size Recommendations

Zeiss ZE Gear B (except 100 Makro which is C)
Zeiss ZF.2 21 and 35mm / Gear A
Zeiss ZF.2 35mm, 50mm and 85mm / Gear B
Zeiss ZF.2 100mm / Gear C

EF mount Voigtlander 20mm and 40mm / Gear B

Micro 4/3 Voigtlander 10.5mm, 17.5mm, 25mm, 42.5mm / Gear A

Canon 14mm f/2.8L / Gear C
Canon 16-35mm f/2.8L II / Gear B
Canon 16-35mm f/2.8L III / Gear C
Canon 20mm f/2.8 / Gear B
Canon 24mm f/1.4L / Gear C
Canon TS-E 17mm f/4 / Gear D
Canon TS-E 24mm f/3.5 / Gear B or C
Canon TS-E 45mm f/2.8 / Gear B or C
Canon TS-E 90mm f/2.8 / Gear B
Canon 28mm f/1.8 / Gear B
Canon 24-70mm f/2.8L II / Gear C
Canon 28-70mm f/2.8L / Gear C
Canon 24-105mm f/4L IS / Gear C
Canon 35mm f/1.4 / Gear C
Canon 35mm f/2.0 / Gear A
Canon 50mm f/1.4 / Gear B
Canon 50mm f/1.2 / Gear C
Canon 50mm f/2.5 macro / Gear A
Canon 100mm f/2 / Gear B
Canon 100mm f/2.8 USM Macro / Gear B or C
Canon 100mm f/2.8 IS L Macro / Gear B
Canon 135mm f/2 / Gear B or C
Canon 85mm f/1.2L II / Gear D
Canon 85mm f/1.8 / Gear B
Canon 70-200 f/2.8L / Gear C
Canon 70-200 f/2.8L IS II / Gear C
Canon 100-400mm f/4.5-5.6L IS / Gear D
Canon 180 f/3.5L Macro / Gear C
Canon 200 f/2.8L / Gear B