BAHCO was the first to create a successful bimetal blade that combines a flexible, shatter resistant spring steel back with a high speed steel cutting edge to provide faster, more durable cutting power. With the latest generation of bi-metal hole saws, we take the technology even further. The cutting edge with 4 to 6 teeth per inch is electron beam welded to a tough alloy back, and then the teeth are precision ground to further increase cutting efficiency. The result is a hole saw that can cut clean, accurate holes in virtually any machinable material. Knockout holes allow easy core removal.