This is a Mamiya RB 150MM F4 "C" Soft Focus Lens. This lens will work on all Models of the RB67 as well as the RZ67 Cameras. This lens is a great short telephoto all by itself.  Add a disk to create the soft effect for portraiture. You have your choice of softness from disk 1 to disk 3.   

This lens is in Excellent Condition as it shows normal wear. There is no fungus & no haze & no separation. Shutter speeds are deliberate and accurate. Comes with the complete set of Disks, front and rear caps, as well as the Lens Hood.