A quality wide angle with outstanding build and smooth operation, even after 50 years. A vintage lens that will out perform many more modern contempories. Very useful focal length - architecture, street work, interiors. This lens is very small, doesn't weigh much and covers most general shooting very well.   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.