Canon 24mm f1.4L II USM is an Auto Focus (AF) Wideangle Prime 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 24mm. Providing a max aperture of f1.4 at 24mm, this lens is very fast.
Canon 24mm f1.4L II USM is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.