Noah and Bernard Zeitmann of Illinois have met their goal of building a collection of solid serial numbered small-size U.S. paper money.

That’s no small task, according to Mike Abramson, owner of Mike Abramson Currency in Duluth, Minn., who specializes in what collectors refer to as “fancy” serial numbers.

But it’s even more interesting when you throw in this fact — these twin brothers are 84 years old.

The collection is officially called the Bernard L. Zeitmann Collection but both brothers own and enjoy it, according to Abramson.

He said the collection is not for sale but the accomplishment should be applauded.

He described the collection as containing “sets of banknotes that in my opinion, makes it as close to a national numismatic treasure as you will ever likely see.”

This collection of solid serial numbered notes features notes for which all of the eight digits in the serial number are identical from 11111111 to 99999999.

The collection focuses on silver certificates and Federal Reserve notes.

It features, for example, Series 1928, 1928A $1, 1935 and 1957 $1 silver certificates, each with solid numbers from 11111111 to 99999999.

The collection also contains solid serial numbered sets of various series of small-size $1, $5, $10 and $20 Federal Reserve notes.

The notes have been graded either PCGS Currency 62 to 66 Premium Paper Quality or Paper Money Guaranty 63 to 66 Exceptional Paper Quality.

For more information about the collection, contact Abramson by telephone at 218-310-0090.

Read more of Coin World's recent paper money coverage:

• Rare 1959 $500 note from Hong Kong bank realizes $32,256 in Spink Aug. 21 auction
• Heritage Auctions to offer serial number 1 $10 national note from Tonopah, Nev., bank