The Spyderco Endura 4 knives have a little more weight but a slimmer handle thickness. They offer the solid back lock mechanism for great strength, just like the FRN Endura knives. Spyderco's Endura knife was one of the first of its kind on the market. The Endura brought lightweight, one-hand opening knives to the market with a price point that just about everyone could afford. They became some of Spyderco’s bestsellers and they haven’t slowed since!