I've had these Gerber knives since the late '70s. They are all in perfect condition, although the sheaths have some wear. The blades will all shave like a razor. I don't use them, but aren't getting rid of them, either. I have plenty of utilitarian blades around. Not counting the small folding knife, the bottom one is a Mark I; the edge extends around the point but not up the back side of the blade, with a boot sheath. The middle one is a TAC II with a molded sheath and a push-button lock that holds the knife in the sheath through a latch on either side of the finger guard. You press the button with your thumb as you grasp the knife. The top one is a Mark III, a longer version of the Mark I with serrations and edge on both sides of the blade. The sheath has a pocket with cover for a sharpening stone.