A quality wide angle with outstanding build and smooth operation, even after 50 years. A vintage lens that will out perform many more modern lens offerings. Very useful focal length - architecture, street work, interiors. This lens is solid metal, and being very small, doesn't weigh much. An aperture preset function allows the desired maximum aperture to be preset. Both the aperture and focus rings have good feel and smooth function.   This example has been very well cared for. Optically and cosmetically A. You can buy this lens for your M42 screw mount Pentax or choose the option of adding a K&F precision M42-E adapter which enables this lens to be mounted on Sony E-mount, focus peaking cameras. Both lens caps supplied.