Seal the end of 4 in. single-wall corrugated pipe with the HDPE Corrugated End Cap. The drain fitting is also used to close off the 4 in. slotted pipe in the EZflow® Gravel-Free French Drain System (EZ-1001F). This cap is used to seal off the end of pipe to stop the flow of water. The corrugated end cap is made of high-density polyethylene (HDPE). Meets applicable ASTM standards. For use in non-pressurized underground sewer and drainage applications; maximum working pressure of 5 psi.