DerbyDad03 wrote:

PEX-AL-PEX pipes, or AluPEX, or PEX/Aluminum/PEX, are made of a
layer of aluminum sandwiched between two layers of PEX.

That's the pex I worked with 8 years ago for a small plumbing project.

So in my mind, pex is always an alumimum pipe sandwiched between two
plastic layers.

Um...your mind is wrong.

Read what you posted. You didn't use PEX, you used PEX-AL-PEX or
AluPEX, or PEX/Aluminum/PEX which is made of a layer of aluminum
sandwiched between two layers of PEX.

Calling that PEX is like calling a grilled cheesed sandwich "bread".

That's what I bought at Home Despot - and they were calling it pex. At
the time, I think that's the only form of pex they were selling for
residential / do-it-yourself plumbing.

And if you ask me, I would never buy just the plastic tubing (the
so-called "real" pex) for any plumbing projects, given that the "AluPex"
is available and is a whole lot stronger given the aluminum layer.