As far as we can tell, this is the only necklace out there with an antibody and virus that actually fit together in the antigen binding site. If you look closely, you'll see amino acid chains, regions, disulfide bonds, and other features as well. Pewter cast from hand-carved models, these are solid, eye-catching pieces that will be the talk of the lab. The larger piece measures about 1.5 inches at it's widest points. Put them both on one gunmetal chain, or split them up for the most epic science themed friendship necklaces ever. Short chains are 18 inches, long chains are 32 inches.