Bidspirit auction | United States - Modern Errors

United States - Modern Errors and Varieties - 1989, 100th Anniversary of the Montana Statehood, five imperforate progressive proofs of 25c in blocks of four, all mounted on large USPS page with explanation of colors underneath, fresh, VF and extremely rare, only a few such pages were produced for presentation purposes, Est. $3,000-$4,000, Scott #2401