How Identify right Oxygen Barrier PEX tubing?

From what I'm reading you have found a coil of PEX tubing in your garage and your trying to identify it. There are a few tips for identifying PEX piping, for one you stated that the coil you found has a matte surface, this automatically rules it out from being oxygen barrier. Oxygen barrier PEX has a glossy surface and is always sold in a white, red, or orange color if it is PEX-AL-PEX. The markings on the tube are usually how you determine what type of PEX it is, but there is always alternative options. Non-barrier PEX is easy to specify due to its matte look, and the colors only determine if they are for hot or cold lines.

Oxygen Barrier PEX tubing is glossy with visible white layer inside the pipe, Non-barrier PEX tubing is matte and usually blue color.