Oxygen Barrier Pex??

[Mark Smith]

Hello all.  I recently had a local plumbing & heating company come inspect a boiler and water heaters while I have a house under contract.  The plumbing & heating company noted that the pex used on the boiler was not oxygen barrier pex, and needed to be swapped out.  The next day the seller contacted me, saying he checked out the pex and believes it IS oxygen barrier.  Can anyone tell me how I can tell the difference, if there is a way?