This is a Pentax M42 screw mount lens. (I'm borrowing the Pentax K mount tag, but please note that it cannot be attached to K mount without an adapter.) This is a 300mm lens, which was rare for lenses of that time. Back then, 300mm was considered a super-telephoto lens, and it seems that there were not many buyers and not many of these lenses still exist. I purchased this item in 2022 at a store-exclusive sale at Fujiya Camera in Nakano, Tokyo. It was displayed on the 2nd floor of the main store, not in the junk section, so I believe it was thoroughly checked by professionals at that time. I haven't used it recently and have stored it in a dehumidified storage box, so I haven't taken any actual photos with it. Therefore, I am selling it as junk. Returns are not accepted to prevent swapping. The lens appears clean to the naked eye, but dust can be seen when a strong light source like an LED light is shone on it. There is no mention of mold or cloudiness on the purchase receipt, so I don't think it will affect the photos, but I cannot guarantee it as mentioned above. The exterior has been retouched where the hood is chipped. I will include the warranty card (expired) as proof of purchase from the physical store. Accessories include a front cap, rear cap, and protective filter. Thank you.