The Hydrophobia 300-600 is a heavy duty rain cover for a DSLR with an attached 300/f2.8 to 600/f4 size telephoto lens. Made from waterproof seam-sealed material, the cover mounts to the lens hood, so can be rolled back when not is use, but quickly replaced when it rains. A tethered lens hood cover keeps moisture or debris from hitting the front lens element while the camera is not being used, and tucks away into a side pocket. 600/f4 or 800/f5.6 lenses use a supplied extension cover. There is easy access to all controls, and an clear eyepiece cover which can be lifted if required. n.b. a camera-specific Think Tank Eyepiece is required to attach the cover to camera.