I think they're Metalform mags, but don't hold me to that one. I'm a Wilson or Tripp Cobra guy, but these work just fine in the Sig.
For the money I paid, I don't think I've ever gotten a gun for the money that this one is....at least so far.
Gen 3: G19,G20,G23,G26,G27,G29,G30,G30S,G32*,.50GI
Gen 2: G19
Gen 4: G17,G22
Gen 1: G17
NRA Life Member. www.1911addicts.com