Black Diamond has been doing cams since Christ was a private, but the C3 is relatively new for them: a three-lobe cam to complement the recently redesigned C4 that has – wait for it – four lobes.
The C3 comes in five small sizes, 000 to 2, each color coded. They extend the size range of the C4s perfectly, and feel similar: slightly stiffer than some other models, but a nice feel when placing. The integrated webbing goes through a wire loop that provides great purchase for your thumb. The action is a little stiff, but on the plus side they don't walk much.
They're a little bit pricey, but I can tell you from experience BD cams last forever. I've still got plenty of my original double-stem Camalots around and they work great.