This is play money, like Monopoly Money and is not based of the US dollar but is based of of the Chinese Bill of the 1920s era. A back will eventually be provided, but printing each bill ($1, $5,$10,$20,$50, ect) in a different color paper should suffice for most gaming needs.
Use them as you want for RPGs, or playing poker in a 1920s vibe. They should be bigger than modern bills as that's how it was in the day.
Seal is from Propnomicon propnomicon.blogspot.com/