This version of the Spyderco Sage 5 uses CPM SPY27 steel, which has extreme hardness and edge retention. The Sage 5 also highlights Spyderco's own patented Compression Lock, which uses one of the handle's stainless steel liners, the stop pin, and an upward-facing ramp on the blade's tang to create an incredibly strong and user-friendly lock mechanism. Skeletonized, nested steel liners and FRN handles provide exceptional strength while keeping things light.