Oxygen Barrier (EVOH) is used for residential and light commercial radiant heating applications. With the same properties as PEX non-barrier pipes, EVOH PEX barrier pipe keeps oxygen and other elements from infiltrating and corrupting the key mechanical components in heating systems. Pexflow PFR-R1100 Pex Tubing is a strong and flexible cross-linked polyethylene tubing with superior temperature and pressure ratings that is useful for plumbing project in commercial and residential hydronic radiant heating applications. PEX-B is made using a "Silane" or "Moisture Cure" method of crosslinking, where links between the molecules of the HDPE polymer are formed after the extrusion process using a catalyst and by exposing PEX tubing to water (steam bath). Color: Red. Material: Cross-Linked Polyethylene (PEX).