Dry Fit, NO GLUE! Introducing the ultimate solution for connecting 4" corrugated pipe to any 4" smooth wall PVC pipe - our HDPE coupler. Built to last, our coupler is made from the strongest material on the planet, HDPE, which boasts a lifespan of up to 500 years. It has a lifetime guarantee not to crack. Not only is HDPE durable, but it's also flexible enough to withstand underground buried downspouts, which is crucial when the ground settles and shifts over time. Includes (2) of FDM's Fasteners