Oatey KnockOut Test Caps are a solvent weld test cap designed for use on Schedule 40 ABS or PVC DWV piping for testing up to 17 PSI or 40 head pressure KnockOut Test Caps deep design provides strong, leakfree connection, while tab feature keeps hands free from solvent cement KnockOut center of test cap can be removed with tab to prevent possible blockage in piping