2018 Loonie R&D Lab Double Concave Dollar 10OZ Silver Proof Coin. Applies the new technology from the Research & Development Lab.Edge thickness is over 16mm, so thicker than the 1 kilogram coins. Piedfort coin is concave on obverse and reverse with 6.3mm of curvature on each side. 11-sided common loon obverse has security repeating field of concentric maple leaves. Composition 99.99% pure silver. Artist : Robert Ralph Carmichael (reverse), Susanna Blunt (obverse). This item is in the category "Coins & Paper Money\Coins: Canada\Commemorative". The seller is "tmiha" and is located in this country: CA. This item can be shipped to Canada, all countries in Europe, all countries in continental Asia, United States.