The Chrosziel Gear Ring for Canon's EF 24-70mm Lens attaches onto the focusing ring of Canon's 24-70mm lens and outfits the lens with a 0.8 pitch gear so that a follow-focus system can be fixed into the 0.8 teeth. The follow-focus can thus be used with the Canon lens to achieve precise focusing and zoom.
The Gear Ring is split along a point of its 83.6mm diameter. The split allows the Ring to be opened up to resemble the letter "C" and as a result to easily attach onto the lens. Once on, a screw at the split point securely tightens the Ring onto the lens.