eNVIROMENTAL, eTHICAL, eCONOMICAL, eASY AS. Moana Rd's reusable stainless steel mugs are double walled and insulated. The eMug inner and outer material is made food grade 304 stainless steel. It is BPA free, reusable and environmentally friendly. Our new eMug Slim is designed to fit in most car cup holders.