Bi-metal hacksaw blades are significantly more durable than regular hacksaw blades and are almost impossible to break. Precision ground teeth improve the blade's durability and performance when sawing most hard materials. The blade is suitable for 300 mm (12") hacksaws. 24 TPI (teeth per inch) Bi-metal hacksaw blades can be used to cut most hard materials. The blade is best suited for 2 - 5 mm thick: aluminum, bronze, copper, brass, hard plastics, cast iron, steel and stainless steel.