5c-50c 1918-34 Air Post, "Specimen" Ovpts. (C1S-C2S, C4S-C6S, C7S-C9S, C12S, C17S-C19S).
12 total, four with overprint in purple, others in black, unused (no gum), few with blue crayon "check" marks, few small faults, Fine-Very Fine, a rare and desirable group, five with 1977 B.P.A. certificates
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