High grade 1902 Red Seals are tough notes. One can spend years trying to complete a nice type set. Also, as the denomination increased, so does the rarity. Typically, when national banks requested $20 bills from the Treasury Department, they were usually printed in sheets of $10-$10-$10-$20. So right off the bat, large size $20 national bank notes were 3 times rarer than $10 notes and four times rarer than $5 notes (printed in sheets of $5-$5-$5-$5). $50 and $100 were usually printed in sheets of two ($50-$100) and are exceptionally rare. Combine this with the fact 1902 Red Seals are one of the RAREST large size nationals extant, finding high grade examples can be a challenge.