A weapons-grade ring of electrorefined plutonium, typical of the rings refined at Los Alamos and sent to Rocky Flats for fabrication. The ring has a purity of 99.96%, weighs 5.3 kg, and is approx 11 cm in diameter. It is enough plutonium for one bomb core.  The ring shape helps with criticality safety (less concentrated material).
Los Alamos National Laboratory
Attribution
Scanned from: <cite style="font-style:normal">Christensen, Dana (1995). "<a rel="nofollow" class="external text" href="http://la-science.lanl.gov/lascience23.shtml">The Future of Plutonium Technology</a>". <i>Los Alamos Science</i> (23): 170.</cite>