3/4″ Poly Female Pipe Thread Insert Adapter, Plastic x Female. Poly insert fittings are connected to PE Polyethylene pipe with stainless steel clamps. For use with COLD water only. Do not use with compressed air or gases. Do not use in a dwelling. ASTM D-2609 Listed. NSF 14 and 16 Listed for potable water services. Fitting modifications voids warranty.