Pentax DA 18-50mm F4.5-5.6 DC WR RE is an Auto Focus (AF) Standard Zoom lens with APS-C / DX max sensor coverage. When mounted on a APS-C / DX sensor camera, it will give you an FF equivalent focal range of 27 - 75mm. With a max aperture of f4 at 18mm, we can not consider this lens fast on wide end and neither at tele end with its f5.6.
Pentax DA 18-50mm F4.5-5.6 DC WR RE is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.