Insulated Container & Spork Purple, N/A,Interior of the GO4TH and exterior are made from 304 medical grade stainless steel. Specifically 18/8.The containers are double-walled and vacuum-sealed to achieve their insulation. The inner cap is made from polypropylene and is fitted with a silicone washer. The fork that is embedded is also made from 304 stainless steel and has a TPR (thermoplastic rubber) handle. The product contains no inner chemical sealant, it is just 304 stainless steel.