This set of two dog tags come with chains.  The first dog tag is engraved with "Toxic Water Survivor with the US Flag/Skull flanked the the Biohazard Symbols."  The second dog tag is engraved "For all those that have drank the water and have not been affected."
 
Each dog tag is about 50 x 29 x 1 mm/ 2 x 1.1 x 0.04 inches, and the round hole of the disc is approx. 3 mm/ 0.1 inch in diameter. They are sturdy and reliable, not easy to break or fade, and lightweight for wearing.