John Glenn - „Sieger“ stamp block

From the infamous series of 20 hand-signed stamp blocks issued by German stamp dealer Sieger in the early 70s - these stamp blocks are considered the first big commercial signing the astronauts (then Mercury / Gemini / Apollo) did! 

John Glenn hand-signed "Sieger" stamp block + Sieger COA! (mint - not hinged)

These stamp blocks also represent the only commercial signing Neil Armstrong ever did before he stopped signing philatelic items. It was also the stamp block from that series that caused Jack Swigert to be bumped from the ASTP prime crew for denying having these signed for money (then each astronaut got $5 per block).

The story is well described in various astronaut autobiographies such as "The All American Boys by Walt Cunningham", and "Carrying the Fire by Michael Collins" and mentioned in several other books as well.

Today it is believed that originally 500 of these complete sets were then offered by Sieger.