Nikon 17-55mm f2.8G ED-IF is an Auto Focus (AF) Standard Zoom lens with APS-C / DX max sensor coverage. When mounted on a APS-C / DX sensor camera, it will give you an FF equivalent focal range of 25.5 - 82.5mm. With a max aperture of f2.8, this lens is fast on wide end and equally fast at 55mm with a max aperture of f2.8.
Nikon 17-55mm f2.8G ED-IF is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.