This looks like the ultimate utility knife. The SpeedPak from Clauss, uses replacement blade cartridges. Carry a cartridge in your pocket and when needed, just pop it into the knife. This seems easier and safer than messing with individual blades. Each cartridge holds 10 Titanium Bonded double-edged blades that are 3x harder than steel and stay sharper longer. You can buy the knife and one cartridge for $15.