The AF-S NIKKOR 400mm f/2.8G ED VR Lens from Nikon is a premium, fast telephoto prime lens for the Nikon autofocus system. It is designed for full frame DX format DSLRs and is also compatible with FX format cameras, providing a 600mm focal length equivalence on crop sensors. It is a very robust and durable lens, incorporating a magnesium die-cast barrel and professional-grade dust and moisture sealing for use in rugged situations.