Certa-Lok PVC Well Casing utilizes CertainTeed's spline-locking design to form a full-strength joint instantly in all weather conditions - no solvents, arc welding or reinforcement joints are required. Certa-Lok is available in a wide variety or sizes and wall thicknesses for installation in wells with depths of 1,000 feet or more. Additionally, the company recently introduced its small diameter (4 inch to 6 inch) Integral Bell Well Casing, which is supplied with a conventional belled-end joint to help provide faster assembly. CertainTeed Corp., Card No. 301