The cup body is made of double-layer 304 stainless steel, and the cup cover is made of national standard food grade PP material.The sealing ring adopts national standard food grade silica gel, which is safe, hygienic, anti-corrosive and rust-proof.The surface of the inner liner of the bottle is electrolytically ground to effectively prevent the generation of dirt.The surface of the outer shell of the bottle is treated with a non-sticking process;Patent ZL2012 3 0279198.3