Rota Nack Knife The Hand Knife with 30 Cutting Edges - Safe and easy to use This 15-blade cartridge-in-handle gives you a new cutting blade with the twist of the knob There's no need to touch the blades. The factory loaded cartridge of blades is already inserted into the knife ready to go. Comes with pre loaded 15 blade cartridge 30 cutting blades, each blade has 2 cutting edges, simply turn the cartridge around to access more.