Product details:

Replaces Stock Foot on Lens Collar, Provide Arca-Swiss Type Quick Release, Two Safety-Stop Screws, Constructed of 6060 Aluminum Alloy, Fits Version II Canon Telephoto Lenses. The CLF456 Replacement Foot for Select Canon Lenses from NatureScapes replaces the stock foot of your large telephoto lens with this Arca Swiss-style foot for easy attachment to a corresponding quick release clamp. The replacement foot is made of strong 6060 aluminum alloy and provides greater stability and easier removal. Two removable safety screws prevent the lens from sliding out of the clamp in the case of inadvertent loosening. Note that for certain legacy lenses shorter screws may be necessary.