N-12 WT IB's polymer composite joint combined with HDPE's excellent abrasion and corrosion resistance, produces a joint with excellent strength. The wide proprietary polymer composite is fused to the outside wall of the built-in bell, improving the joint's integrity and tolerance control. With its integral built-in bell and factory-installed gasket, the pipe requires no extra couplers, grout or other sealants to install. The joint meets or exceeds ASTM 3212 lab test and ASTM C969 watertight field test, which helps fill an essential role in meeting the new, stricter/environmental Protection Agency guidelines. N-12 WT IB pipe is so advanced in its design, it is easy to install and easy to put your confidence in for long term reliability.