1.material:good quality natural rubber 2.density: medium and hard 3.size:10-170 4 withstand high temperature Standard sponge ballsDescriptionThe ... their first choice.Our standard balls have 5 kinds of different firmness. They are soft, mid-soft, medium, mid-firm, ... sootStabilityNot available with acids, alkalis, oils, fats and solvents. High quality rubber sponge cleaning ball for pipeline cleaning