PENTAX15-30mm F2.8 ED WR is an Auto Focus (AF) Wideangle 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 15 - 30mm. With a max aperture of f2.8, this lens is fast on wide end and equally fast at 30mm with a max aperture of f2.8.
PENTAX15-30mm F2.8 ED WR is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.