Hole saw variable pitch bi-metal 3-1/2"

Variable pitch hole saw, made of bi-metal. Cuts through steel, tin, aluminum, fiberglass, wood and plastic. Extra-tough bi-metal blade ... we use the highest grade of tool steel to outlast competitor's blades. That beats premature saw replacement and saves you money. Steam oxide finish ... no paint to gum up and slow cutting. The saw runs cooler for longer life and better performance. Extra-thick back plate minimizes vibration for smoother, easier, less tiring cutting.