“The Nack” knife is different from other utility knife tools, because it holds 15 blades pre-loaded in the hilt. That little feature makes it easy to switch out a dull blade for a new sharp one without taking the knife apart. Which saves you time and gets the job done quicker.
Just retract the blade, turn the end cap and slide a new blade out. One downside is that this means you also have to buy replacement cartridges from Nack Products for $6. The Nack will cost you $16 by itself. It comes in two versions: one is black with a soft grip, and the other is metal and carries the additional title of Pro.