About the AP-501 Replacement Lens FootThe AP-501 replaces the stock foot on Sony Lenses (See list below, Image of compatibility chart, or our website). The AP-501 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 Nikon 70-200 f/2.8 Z VR S-line, 100-400 f/4.5-5.6 Z VR S-line, 400 f/4.5 Z VR S-line LensesWhat's IncludedAP-501 Arca-Swiss Style replacement lens foot (Qty 1) Mounting Screw – ¼-20 x 9/16L 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)10 Year Warranty on all products from WimberleyAbout Wimberley Replacement FeetWe 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