... W2, screw is made of galvanized iron, head hoop and steel belt made of 200/300 series stainless ... /W4≤0.6≥8 Description:W1--screw, head hoop and steel belt are made of galvanized ironW2--screw ... is made of galvanized iron, head hoop and steel belt made of stainless steelW4--screw, ... belt are made of stainless steelW5--screw, head hoop and steel belt are made of 316 stainless steel ...