Bosch HSS Bi-Metal Hole Saw features Progressor tooth design that cuts faster, cleaner and lasts longer in wood and metal applications The reinforced shoulder adds strength and 8% cobalt alloy built gives it a longer life and higher heat resistance This hole saw works with standard or Quick Change mandrels Made with 8% cobalt alloy for longer life and higher heat resistance Rpm for Wood – 2000, for Metal – 140