This Cherne 355-168 Muni-Ball Plug features a natural rubber construction that is known to have higher resistance to abrasion, wear, and water. This test ball is sturdy, rough and efficient on most types of pipe. It is also excellent for repair and installation of residential or commercial piping systems. Oatey takes pride in providing their customers with quality products that are dependable and applicable for all of those who use them. These replacement parts and accessories are developed to both perform and to last the way that they are intended to.