2016 Canada $20 Superman vs. Batman 1/4 oz .9999 Silver Coin - Gem in Sealed Flip w/ COA PF-18/Cr. 436 and one-half dollar clad coins

and one-half dollar clad coins will have a shape such that the obverse is concave and the reverse is convex

Inscriptions are “UNITED STATES OF AMERICA

baseball fans "might have called Lou Gehrig the white Buck Leonard

the Apollo - Soyuz Test Project

From the Wikipedia Page on Willy Ley:

2016 Canada $20 Superman vs. Batman 1/4 oz .9999 Silver Coin - Gem in Sealed Flip w/ COA PF-18/Cr. 436 and one-half dollar clad coinsIn original flip with all Certificates of Authenticity. Mintage 300,000 Composition 99. 99% pure silver Finish specimen Weight (g) 7. 96 Diameter (mm) 27 Edge serrated Certificate not serialized Face value 20 dollars Artist DC Comics (reverse), Susanna Blunt (obverse)