two binders arranged by denomination, for each stamp in the series there is a wealth of production material including trial color proofs with Waterlow overprints, the issued souvenir sheets with manuscript "File Copy", "Muestra" overprints, imperforate proof sheets, as well as on-cover uses (mostly philatelic), generally very fine, many of these items only exist in extremely limited quantities (for the imperforate sheets as few as three are in private hands), an extraordinary opportunity for the baseball or sports topical collector, or someone looking to purchase the foundation of a strong exhibit-quality collection