Nikon 200-400mm f4G ED-IF VR is an Auto Focus (AF) Telephoto Zoom lens with 35mm FF max sensor coverage. When mounted on a 35mm FF sensor camera, it will give you an FF equivalent focal range of 200 - 400mm. With a max aperture of f4 at 200mm, we can not consider this lens fast on wide end but f4 at 400mm is not too bad for tele end.
This lens features on optical image stabilization which helps capturing sharper images at lower shutter speeds. Nikon 200-400mm f4G ED-IF VR is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body. Nikon 200-400mm f4G ED-IF VR was replaced with Nikon AF-S Nikkor 200-400mm f4G ED VR II. Follow the link to read our comparison of these cameras: Compare Nikon AF-S Nikkor 200-400mm f4G ED-IF VR vs Nikon AF-S Nikkor 200-400mm f4G ED VR II