Feature●Lightweight aluminum construction; adjustable rubber-lined metal band firmly grips zoom or focus lens rings●Works like a follow focus; end wheel finger grip makes very smooth lens moves●4.5 inches handle length; fits lens rings from 50mm to 80mm diameter●For full lens zooms or deep focus pull actions, this device is superior; it easily covers the full lens ring range without pauses or extreme wrist twists required with a follow focus, and it can produce ultra slow zooms like a pro camcorder●Not applicable for really fast (fat) lenses like f-1.4 as these lens rings are too largeDescription The ALZO Smoothy Zoom / Focus Assist is a very low cost device that easily attaches to DSLR lens rings and allows for smooth zooms and focus pulls. It is a good replacement for a follow focus at a fraction of the cost. For full lens zooms or deep focus pull actions, this device is superior. It easily covers the full lens ring range without pauses or extreme wrist twists required with a follow focus. Fits Lens rings from 50mm to 80mm diameter.