Sigma 24-105mm F4 DG OS HSM is an Auto Focus (AF) Standard 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 24 - 105mm. With a max aperture of f4 at 24mm, we can not consider this lens fast on wide end but f4 at 105mm is not too bad for tele end.
This lens features on optical image stabilization which helps capturing sharper images at lower shutter speeds. Sigma 24-105mm F4 DG OS HSM is not a weather sealed lens, so you have to be extra careful against rain and dust.