The SmartShape Base Layer Crew Neck is made with an environmentally friendly treatment called ChitoSante, This is a new environmentally friendly treatment that is made from a natural biomass called ChitoSante. ChitoSante is made from crab and/or shrimp shells. ChitoSante is absorbent, breathable, durable, fast drying, soft, static free and easy to handle. Along with these benefits, ChitoSante has natural and durable anti-bacterial properties. ChitoSante strongly inhibits the growth of bacteria. ChitoSante treated fabrics stay fresh, hygienic and odor resistant. ChitoSante is the only anti-bacterial bio-agent in the world that is certified by the US Environmental Protection Agency.