National Seal Company is a manufacturing an installer of DURA SEAL® HD (high density polyethylene), COEX SEAL®, FRICTION SEAL®, DURA SEAL® LL (linear low density polyethylene) geomembrane liners; POLY-NET® drainage nets; TEX-NET® geocomposites; and Bentofix® Geosynthetic Clay Liners (GCLs).