3/4 in. nylon insert elbows are used to join two pieces of poly pipe on a 90 degree bend. These fittings are for cold water applications only and can be used underground and above ground for water service and agriculture uses. They are NSFapproved. Nylon insert fittings are tougher and will absorb shock better than poly insert fittings. Use stainless steelhose clamps to join fitting to pipe.