Forgive my ignorance for calling them penny fliers, they are Japanese... so I guess that makes them "Yen fliers"? The website calls them Mini- airplane museum series. Anywho, there are models of aircraft from 1884 to 2000 with many countries represented, and even a flying Formula 1 ! PRETTY COOL!!!!! http://www.venus.sannet.ne.jp/eyoshida/a.htm you may want to use an online translator so you know what you are getting. I believe the weight of the coin used was 0.1g .