This is one of the sharpest medium format lenses ever made - the 300mm f2.8 APO A series manual focus lens for mamiya Pro-TL or other 645 cameras.  But you are likely to use it on the Fujifil GFX100S series medium format digital cameras where it performs superbly (yes, we have tried it)   Superb construction and special glass means this lens would likely cost over $20,000 if made today.  Mint condition in original case with hood.  Add $160 for an adapter to Fujifilm GFX series cameras.

Mamiya 300/2.8 APO A lens for M645