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MWSpaldings (aka, "Sports Company of America" Champions) were issued two years -- 1926 and 1927.
In my estimation, the majority of presently known, high-grade 1926 Spaldings came from one of two major hobby finds:
1) Approximately 500 cards with advertising backs discovered by Alan Hager in the late 80s/early 90s.
2) Approximately 500 regularly issued cards with biographical and statistical reverses uncovered by us (BMW Sportscards) in the mid-1990s.  One "Mint" (nearly complete) set of 190 different including the original cellophane envelopes and scrip cards was assembled.  Most cards in the master group of 500 were NM/MT or better and included about 100 baseball players.  Nearly every high-grade (NM/MT or better) 1926 Spalding Babe Ruth that is presently known in the hobby originated from this find.
To date, Spaldings from the second year, 1927, comprise a single card -- a 1927 Babe Ruth in Vg-Ex condition.