Oatey Knock-Out 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. Knock-Out Test Caps deep design provides strong, leak-free connection, while tab feature keeps hands free from solvent cement. Knock-Out center of test cap can be removed with tab to prevent possible blockage in piping.