Olympus 300mm f2.8 is an Auto Focus (AF) Telephoto Prime lens with FourThirds max sensor coverage. When mounted on a FourThirds sensor camera, it will give you an FF equivalent focal range of 600mm. With a max aperture of f2.8, this is a fast lens.
Olympus 300mm f2.8 is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.