... strong alkali, salt, ammonia, chlorine, and environment of water, more dust and humidity.4.They are widely used in ... lines of petroleum, chemistry, dock, food, medicine,warinsustry and so on.Features1.It is casted into shape with ... has the feature of water-proof, dust-proof and corrosion-proof, terminal is not provided inside the ... .According the user's demand, make steel casting and engineer plastic.