Watch List notes:

Keystone Aircraft Corp. Proof Stock. Pennsylvania. ND (ca.1926), Odd Shares, Proof stock certificate of title, text and vignette with no borders. Purple "Cancelled" hand stamps. Vignette of early tri-motor mono-plane. VF condition with archival notations in crayon listing status of printing plate. Rare certificate found in this format only, no specimens or issued certificates available. Extremely rare early aviation certificate. Founded in 1926, it was taken over in 1929 by Curtis-Wright where it was part of their manufacturing division and was closed in 1932. Historic aviation certificate, 2 found in archive. Republic BNC.

Estimate: 200-400