Made of tough elastomeric polyvinyl chloride (PVC), the flexible couplings are strong, resilient and unaffected by soil conditions. They are also resistant to chemicals, ultraviolet rays, fungus growth, and normal sewer gases due to the inert nature and physical properties of the PVC material. Fernco flexible couplings are leak-proof, rot-proof and seal against infiltration and exfiltration, giving you confidence in your pipe connections.