Tamron 17-35mm F2.8-4 Di OSD is an Auto Focus (AF) Wideangle 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 17 - 35mm. With a max aperture of f2.8, this lens is fast on wide end. The long end is also quite fast at f4.
Tamron 17-35mm F2.8-4 Di OSD is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.