One of the centre pieces of my Apollo Soyuz mission collectables includes this presentation featuring a piece of flown kapton foil from the command module of the American Apollo 18 space craft used in the ASTP mission.
Special commemorative "Partners in Space" philatelic numismatic presentation with limited edition sterling silver proof medal commemorating the Apollo Soyuz joint mission.
This is both the Soviet and American versions of the same Fleetwood philatelic numismatic cover both with their respective stamps and cancellations. The medal has a Soviet side and an American side which are both facing on their respective covers and looks very similar to a MACO medal but smaller in size to fit the envelope.

Both are limited editions, 1500 for the Soviet cover and 4600 for the American one. Both covers contain the same sterling silver proof medal commemorating the Apollo Soyuz joint mission (I also have a second PNC featuring the bronze medal of the same design). Also pictured is a copy of the Apollo Soyuz information booklet and letter from Fleetwood that accompanied these PNCs when they were distributed to collectors.

Here are a pair of American and Soviet PNCs featuring sterling Silver medals of the two crews and an image of the docking on the reverse.

This pair of covers were obtained from different sources and was fortunate in both being addressed to the same person.

This is number 12 of a limited edition Frontier Mint PNC that combines an Artcraft cachet (qv) featuring a silver Lombardo Mint medal (qv).
This is a Postmasters of America philatelic numismatic cover with limited edition sterling silver proof medal in a presentation page.
The International Society of Postmasters produced this limited edition Soviet philatelic numismatic cover with sterling silver proof medal.
Here is a further Apollo Soyuz PNC, this one featuring a bronze commemorative medal (listed separately on the medals page) and Space Voyager cachet.
This is a special presentation of Fleetwood FDCs, PNC and information booklet with stamps and cancellations from both sides.

The PNC is the same as the American one above and is number 1677 of 4600.