Tokina AT-X 14-20mm F2 Pro DX is an Auto Focus (AF) Wideangle 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 21 - 30mm. Providing a max aperture of f2 at 14mm, this lens is remarkably fast on wide end. Even better, having an aperture of f2 on tele end, this lens is exceptionally fast through out its range.
Tokina AT-X 14-20mm F2 Pro DX is not a weather sealed lens, so you have to be extra careful against rain and dust.