3 Blades - Specially positioned to extend gradually closer to your beard, to shave you progressively closer in a single stroke. So close there is less need to reshave, which means less irritation. Patented DLC Comfort Edges - Each blade has a patented DLC comfort edge, so Mach3 glides effortlessly and comfortably across your face. And Mach3 has an advanced indicator lubricating strip with a blue stripe that fades away when you are no longer getting the optimal Mach3 shaving experience. All Mach3 Cartridges fit all Mach3 razors.