... ,which make duct rodder cover sliding on surface,durable,corrosion resistant and has good insulation performance,which make them safe ... 1. Light weight,durable,resistance to acid and alkali,aging resistant,corrosion resistant. 2. High tensile strength and bending properties,which make ... 250,300,350,400,450,500 meters for choice. Material Fiberglass (inner) and high density polytgtkebe(outer) Density 1. ...