I bought this thinking it was a #2 extension tube for Pentax 67.
It certainly accepts Pentax 67 lenses, but the camera side of this adapter doesn't fit the Pentax 67. It looks like a P67 mount, but it's a couple mm smaller.
What camera does it fit? I don't know since I have only a fixed-lens digital camera, a Mamiya RZ67 and a 4x5 here with which to test.
It clearly says "Pentax 6x7" and there's also a "2" on the other side of the tube, but again, it's a mystery as to which camera it will fit. Maybe a Pentax 645?
If you know, please post here.
Meantime, I'm offering this for $20.00 USD shipped to anywhere in North America; overseas at cost.