My order arrived today.
The use of a polymer sheath at the front of the mags is a stroke of genius allowing the use of poly on poly without modifications. It is affixed to the metal mag by mechanical means, there is polymer inside the tube the full length of the mag. Probably molded through holes in the steel using heat.
Something I notice but not seen discussed before is the mag catch engagement areas are asymmetrical, favoring the standard (right-handed) configuration. There is more surface area on the right side of the mag to engage with the catch. For me this is good, although I am left handed I use my pistols stock. I had issues with the other brand of aftermarket mags and their metal catch having low engagement enough to pop the mag if anything touched the mag catch button. I resorted to fitting the aftermarket catch to allow more engagement, but this wasn't fruitful.
Don't know how well these PSA mags will run without live fire testing, something I hope to be pleasantly surprised with. They seem well made.