Saw these on the 'cheap as dirt, we want 'em gone' table at the local shop. I have no use for them, but I thought maybe someone here might and the price was right...so I grabbed 'em.
This is an unopened box labeled 'Shimano XTR cartridge brake shoe set M70/R'. There are 4 cantilever pads and pad holders included. Pad material is designed for ceramic rims.
They can be yours for what I paid (US$10), plus actual shipping (which will likely double the cost).
These are someone else's, but appear to be exactly what I have: