Master Mechanic, 2 Pack, 12", 18 Tooth, Bi-Metal Hacksaw Blade, Shatterproof, Virtually Indestructible, Industrial Quality, Particularly Recommended For Cutting Higher Carbon Or Alloy Steels, Bi-Metal Steel Combines Toughness With Flexibility For Heavy Duty Cutting, Lasts 10 Times Longer Than Carbon Blades.