The wimberley ap 554 replacement lens foot replaces the stock foot on the rotation collar of the nikon 500mm f4 af s i ii vr and 200 400mm f4 af s vr lenses the ap 544 is taller than the wimberley ap 533 and provides greater clearance between the body of the lens and the foot making it easier to use the foot as a handle for your lens its longer length ensures a better balance with smaller dslr camera bodies and its also compatible with all pro and pro sumer nikon camera bodies eve