The Knife Blade adds a new dimension and allows you to cut thicker materials such as heavy chip board, mat board, leather (up to 2 mm), bass wood and balsa wood (up to 3/32)! The Knife Blade has Intelligent Variable Pressure. If you are cutting a thick material, the knife blade will take multiple passes- it starts with a lighter scoring pass, another heavier pass will get into middle and then, towards the end of the cutting, it will cut lightly again. This helps you get the cleanest cut possible and mimics how you would cut if you were doing it by hand. This variable pressure helps to optimize the life of the blade as well. The knife blade is compatible with the Cricut Maker machine only. Replacement blades are sold separately.