All Aero Precision M5 uppers are on "DPMS High" pattern. DPMS changed to the "low" pattern in the early 2010's, and just fucked everything up by doing that. There's only one rail manufacturer that I know of that ONLY makes low pattern, and that's GunTec USA. Most other manufacturers make both heights. There wasn't a single Daniel Defense Lite Rail 12.0 for the DPMS pattern made, that wasn't high profile - they didn't get into that "low rail" game at all, before they discontinued that rail.
DPMS High is more prevalent, because it was "most of a pattern" when aftermarket manufacturers started making rails - and that's all it comes to - rail height. Most companies make both. Aero only makes high pattern. They said "Fuk that new junk, because it's junk."
In an industry that "has no SET pattern to follow" for .308ARs, the only consistent thing is that Aero Precision M5 components WORK. DPMS High is WAY more prevalent than DPMS Low, across the board.