The 8512, replaces the 8511, replacing my 8509. The Abzorb SBS in the forefoot is gone. The high Achilles support is gone. The Abzorb in the insole is gone. Much lighter shoe.
Same great breathable fabric. Speed lacing system. It doesn't have the contoured tongue of the 1063! A light shoe, with SL-1 last. Neutral Runner design.  Same roomy toe box. Addicted to spring board affect of ZIP technology.