PM6 is a mysterious 8 subject pin set from 1928, issuer unknown. Small at 3/8 inch diameter, the player selection included 7 Hall of Famers, one of which was Grover Alexander.  Graded PSA 3, the image of Ol' Pete is slightly off center but all there and the surface is quite fresh looking. The pinback shows oxidation, common to the set (common to all pinback issues of this vintage, actually).  The PSA population is 1, this being the sole example graded.  A scarce and very desirable pinback, seldom made available at auction.