Carl Zeiss Distagon T2,8/21 is a Manual Focus (MF) 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 21mm. With a max aperture of f2.8, this is a fast lens.
Carl Zeiss Distagon T2,8/21 is not a weather sealed lens, so you have to be extra careful against rain and dust.