This is a nice bayonet style body cap for the RB67 or the RZ67. Use it while traveling to preserve your lens mount. I always unmount my lenses for travel and cover the exposed areas with caps, it's much safer and extends the life of your camera and lenses.
This one is in mint condition and works perfectly, it's never been used. There are no cracks or breaks in the plastic. It comes in the original plastic bag.