Clauss SpeedPak Replacement Utility Blade Cartridge, 10 Blades Per Cartridge, Red(18089) Cartridge Includes 10 Double Edged Titanium Blades Titanium Blades are 3 Times Stronger than Steel Use with Clauss 18038 SpeedPak Utility Knife Quick and Safe to Replace Incredibly strong titanium blades. Convenient cartridge system for quick and easy replacement. Convenient cartridge system. Double-edged.