1 1/2 in. nylon insert elbows are used to join two pieces of poly pipe on a 90 degree bend. These fittings are for coldwater applications only and can be used underground and above ground for water service and agriculture uses. They are NSF approved. Nylon insert fittings are tougher and will absorb shock better than poly insert fittings. Use stainless steel hose clamps to join fitting to pipe.