This sale is for a mint condition Mamiya RZ67 Extension Tube 45mm (No.1), complete with original box, instructions and end caps.
There are absolutely minimal signs of use. It has hardly been used. It has been tested and the contacts work perfectly and the ring works fine.
This extension tube will give you 0.35 to 0.72x magnification with a 127mm lens.
A copy of the instruction leaflet can also be downloaded from the Downloads section of this website that gives full details of usage (essential for correct exposure if you do not have a metered finder).