mine came from bargain fittings with all silicone o rings, not the black rubber they used to come with...
I think I read somewhere that he was doing that on all his camlocks because of testing done with the rubber ones. Call/email/PM bargain fittings to make sure though.
Like Bobby said, the camlocks have been shipping with silicone gaskets for months now.
The 1/2" NPT size o-rings also work as a replacement if you happen to have bought some camlocks with the black gaskets last year before the switch over to the silicone flat gaskets. - The silicone gaskets are a translucent white color.
We carry the replacment flat silicone gaskets as well on our site.