Unmounted lead-free characters are the most harmless and economical means of positive x-ray identification. It is made of Bismuth which is a chemical element with the symbol Bi and atomic number 83. You can tape these letters to the x-ray film without being worried about contacting any hazardous material. Our letters do not have the interior voids found in some die-cast lead letters. We manufacture these letters in a number of sizes and styles. The Letters or Numbers do not contain any lead material. Other non-hazardous metals are used to form the characters.