Sigma 10-20mm F4-5.6 EX DC HSM 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 15 - 30mm. With a max aperture of f4 at 10mm, we can not consider this lens fast on wide end and neither at tele end with its f5.6.
Sigma 10-20mm F4-5.6 EX DC HSM is not a weather sealed lens, so you have to be extra careful against rain and dust.