Dura Pex tubing question

Is the white Dura Pex tubing with brass fittings and crimp rings Poly?


Dura-Pex is PEX. “Poly” is Polybutylene

Actually, I believe PEX is a “Poly” as well. Polyethylene. However, in the construction industry around here, the terms PEX and Poly have specific meanings as John has described.

Am I missing something. What meaning did John describe?