The C91012 is the Pentax Close-Up Lens #2 for 49mm filter-screw size. It changes the focal length of the camera lens by +500 millimeters. In effect it makes the object much larger and much more detail is evident for critical evaluation. This adapter is for 49 mm filter diameter lenses.
In the Box
Pentax C91012 #2 Close-Up Lens Adapter for 49mm Filter CS-Mount Lenses increases Focal Length by 500mm