This Mamiya 645 No. 2 Extension Tube tube is in overall good condition. This tube has been well used but is mechanically fine, but the rabbits ears (for connecting the aperture prong for use with an AE prism) are missing. This means that you can only use metering in stopped down mode with this tube – but if you are not metering then this makes no difference at all. So, with a waist level finder for example, this tube will work just fine. Dead cheap because of this issue.
This extension tube will give you 0.29 to 0.45x magnification with a standard 80mm lens; a copy of the Mamiya instruction leaflet can be downloaded from the Downloads section. I tend to use this and the #1 and #3 rings just to get a closer focus with my 150mm and 210mm lenses – it is so small that it is no problem to carry around in case you need it.