These Bi-Metal Hole Saws feature M3 high speed steel cutting edges that are electron beam welded to the carbon steel cup. The hole saws have 6 teeth per inch and a positive rake to clear the chips fast and reduce the amount of pressure needed during cutting. You can cut through any machinable metal as well as wood, plastic, drywall, and composites like MDF. The hole saws have a 1-1/2" cutting depth so they will cut clear through 2x4 materials. Saws 3/4" to 1-3/16" have a 1/2"-20 threaded arbor hole while saws 1-1/4" and larger have a 5/8"-18 threaded arbor hole. Made in USA.