Identical design pair in 1.5" size and 3.5" size in high contrast bw without celluloid covering made by button manufacturer for proofing purposes. Only example in the Levin collection. Inscription is "St. Charles, Missouri 1988 Welcomes George Bush." Rim curl reads "Main Street USA Committee." Bush's shoulder at right on 3.5" example has faint trace of tan tone fingerprint mark likely occurring during manufacture. Rest is Mint. Possibly unique.