About the AP-602 Replacement Lens FootThe AP-602 replaces the stock foot on Canon Lenses (See list below, Image of compatibility chart, or our website). When installed this support lowers the overall height of the supported 400mm, 600mm, and 800mm lens by about 1.5". The AP-602 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.Note: This particular plate mounts so close to the lens that it is difficult to use the plate as a handle. Also note IS version I uses the screws from the existing foot for mounting. IS version II uses included mounting screws for mounting. For use on the following Lenses Canon 400 f/2.8 IS version I and II LensesCanon 600 f/4 IS version I and II LensesSigma 500 f/4 DG OS HSM LensWhat's IncludedAP-602 Arca-Swiss Style replacement lens foot (Qty 1) Mounting Screws - M4 x 14mm Socket Head Cap Screw (Qty 4)Safety Stop Screws - M3 x 6mm Socket Head Cap Screw (Qty 2)Hex Key - 3mm T-handle (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