Hitachi 724947 SDS Max 2-1/2-Inch x 39-Inch One Piece Core Cutter Hollow core bit measures 2-1/2-inches in diameter and 39-inches in length Roof-shaped guide teeth (1) ensure improved tool alignment and increased rotational stability Flat hammer teeth (2) are significantly more efficient in this drilling base Hammer hollow core bit is specially suited for modern, powerful rotary hammers Comes with a 30-day limited warranty Fast Bit Penetration Rate High Performer when Drilling Accurate Spot Drilling High Effeciency, Low Weight