I have some Nikon extension tubes and adapters that I have no need for. There are three black extension tubes that are labeled K3, K4,& K5. The larger silver extension is labeled Nikkor F. The 2 pieces on the upper left have a Nikkor F mount. There is a also a Nikon threaded T-Ring? and a Nikon dust cover.
25$ plus shipping for the whole set (will not sell separately).
Thanks for looking,