Cherne® Plumbing Test Ball® Plugs were first introduced in 1953 as a more versatile product than traditional mechanical plugs. Designed to test drain, vent and waste systems Cherne® Test Ball® Plugs could be used in any type of pipe, could be inserted through a test tee, and sealed out of round pipe as well. Cherne® introduced the multi-size yellow-top Test Ball® plugs in 2002. These test ball plugs have the same great features found in the original test ball plugs, but can be used in more than one pipe size.