About the AP-607 Replacement Lens Foot: The AP-607 fits on the stock foot on the Canon 100-500 RF f4.5-7.1 IS. The AP-607 is precision machined to slide right into an Arca-Swiss style quick-release clamp. It also has 1/4" and 3/8" tapped holes for mounting to non-quick-release tripod heads and monopods. All replacement feet feature the same dual safety stops and flash bracket compatibility as our lens plates. For use on the following Lenses: Canon 100-500 RF f4.5-7.1 IS What's Included: AP-606 Arca-Swiss Style replacement lens foot (Qty 1) Mounting Screws – 1/4-20 x 7/16 Flat Head Socket Cap Screw (Qty 1) Safety Stop Screws - M3 x 6mm Socket Head Cap Screw (Qty 2) Hex Key – 5/32 (Qty 1)Hex Key – 2.5mm (Qty 1) About Wimberley Replacement Feet: We use finite element analysis validated by empirical data when we design our feet. This process allows us to optimize the weight to stiffness ratio. Other manufacturers often reduce weight by removing material in ways that are convenient for the machining process or aesthetic design while ignoring stiffness performance resulting in rigidity below our quality standards.Not compatible with most Manfrotto or Gitzo clamps