I am sure I have had this Focal 2x teleconverter since about 1987, using it first with my K1000 and infrequently over the years with other film and now digital cameras including the K10 and K-7. This evening I was just sort of looking for the next photo opportunity (read as playing around) and noticed the dread R markings on this veteran lens accessory.
As I say, I have used this tc a number of times on both a K10 and K-7 and as you can see, the Ricoh pin is the rounded style so I really have no fear of it sticking. But it just demonstrates how pervasive the pin was and that we must be mindful of how it can show it's teeth in many places.
Thank you to those who humor me by reading this little tale. You are now free to move about the forum.