Standard size pex tubing is manufactured to SDR9 standards which is the same outside diameter as copper pipe but has a wall thickness 1/9th the diameter. If you see something advertised like "true 1 inch" or "Not 1 inch OD like others" it is actually metric size. The pipe listed above as 1" ID is 32mm OD and is manufacturered SDR11 standards. This is 1.032" ID which is very close to standard 1-1/4" pex (1.054" ID) but the thinner pex wall allows for more insulation.

NB= Non Oxygen Barrier Pex  OB= Oxygen Barrier Pex

OB usually isn't required unless you are running a pressurized system with no chemicals. It never hurts to use OB pex on an open system (open system has overflow tube at boiler) but is usually just a waste of money and doesn't make any difference.

NOTE:
* Non Barrier pex tubing is either Red or Blue throughout the pipe (inside and outside ).
* Oxygen Barrier pex tubing is either Red or Blue on the exterior but the inside will appear almost white.
(Example: the 3/4" Pex above is Non Barrier and the 1" Pex is Oxygen Barrier ( inside almost white ). )
* All Pex tubing is pressure rated at 80 psi @ 200 degrees and 100 psi @ 180 degrees.
* Our pex is complies with ASTM F876/F877 standards with ROHS certification

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Pex-Al-Pex Tubing

Pex-al-pex is sold as inside diameter instead of copper tube size. It has a few advantages over normal pex. It doesn't expand in length so if you have an installation that can not allow for expansion when the pex gets hot you may want to consider it. Also the sizes fall between pex so it is also a good alternative if you need something a little bigger than 1" pex.

PEX-AL-PEX is made with an exterior layer of PEX then adhesive followed by a layer of aluminum, another layer of adhesive and finally a layer of PEX. The aluminum acts as an oxygen barrier so all PAP tubing is considered OB.