The Irwin Tools 324007- Drill Bit, 1/2 x 24 x 29 Spline 2 Cutter Masonry Drill Bit is a fast and durable bit for the professional user. The bit features a Chrome Vanadium Spring Steel shaft that is through-hardened for Superior Durability. The Shot-peened, double tempered finish reduces breakage. The Bit also features a tip with a Copper brazed material that gives high heat resistance and reduced tip loss. The Spline shank fits all Spline rotary hammers. The two cutter Tip privides faster drilling and dust removal.