OLFA 5009 LB-10B 18mm Heavy-Duty General Purpose Snap-Off Utility Blades (10-Pack). if it's precision you want, choose these OLFA� snap-off blades. They are extremely sharp to begin with, and you can snap off a dulled edge to maintain cutting precision. Use these blades for construction materials including drywall, linoleum, carpet, flooring, insulation and roofing materials.