4 Cutting Edge external edge blade (L10). The L10 HSS blade features 4 cutting edges. Removes burrs from external edges, OD 0.78" (20mm) Two-sided for deburring spiral chips & powdery chips (L10) . The blade features two sides. The "A" side Deburrs materials with spiral chips. The "B" side is for powdery chips. Great for Outer Edge Applications. Good for use on Steel, Aluminum, Copper, Brass, Cast Iron, Stainless Steel, and Plastics. Made specifically for use with the "L" holder.