SIFFO HDPE Double Wall Corrugated Drainage Pipe is a lightweight, corrosion-resistant piping solution designed for non-pressure gravity-flow drainage applications. Featuring a smooth inner wall and corrugated outer wall, the pipe combines efficient hydraulic performance with high structural stiffness. It is suitable for stormwater drainage, sewerage systems, culverts, underground drai... https://www.siffopipeline.com/products/drainage-sewerage-pipe-system/hdpe-double-wall-corrugated-drainage-pipe