Z-WEAR PM consists of:
From Spyderco's website:
Z-WEAR PM is a particle metallurgy cold work tool steel produced in Germany by Zapp. Created to tackle the most demanding industrial applications, it offers wear resistance superior to A2 and D2 tool steels while providing increased toughness and resistance to chipping.
-  Spyderco.com product page: Mule Team™ 30 Z-Wear PM