The Jobu Design Surefoot SF-NX4 7" Lensplate is designed to fit monster sized lenses like the 400mm f/2.8, 500mm f/4 and the 600mm f/4, this 7" long Arca-Swiss compatible lensplate gives you loads of fore/aft adjustment to balance your camera and lens. This Lensplate comes with both - one (1) 3/8" mounting bolt and two (2) 1/4" mounting bolts. No bushings are required. 2 Allen Keys (1/8" and 5/32") are included. 2 Dead-Stop bolts prevent sliding out of the quick-release clamp. Hard anodized, sand blasted finish for years of life. Drilled for fitting most popular flash brackets.