Post Cereals experimented with a large size package design card in 1960 then switched over to a standard sized card for a massive nationwide promotion in 1961.  However, there was also a mail-in offer where you could buy a sheet of your favorite team's players, which could then be easily separated due to factory perforations being deployed.  This latter method avoided all sorts of potential hazards and the factory cards are actively pursued by collectors.  The entire set is still quite popular, Clemente particularly so and it's easy to see why with this PSA 8 that looks as good as it did 60-plus years ago, featuring outstanding color and registration. PSA only has five higher pops, all 9's, with one having a qualifier.