[Practical Set] It comes in 4 most popular bits, 1 pc 3/4” and 1 pc 1-1/8” deburring external chamfer drill bit, 1 pc 3/4” countersink drill bit, and 1 pc 1/4” quick change bit holder. One bit set for meeting your external and internal deburring and chamfering demands. [Tungsten Carbide Blade]: Carbide is a much more superior material than the HSS material that other similar products use. Carbide tools resist abrasion very well. They can also withstand much higher temperatures than steel. Tools with carbide tips maintain a sharper cutting edge better than steel tools. And they generally produce a better finish when cutting, providing a cleaner and smoother cut. In short, Carbide tools cut cleaner, faster and last longer. [Chamfer]: Easily shaves down the outer edges of a screw/bolt/pipe/rod and remove the burr. Quickly repairs damaged bolts and tightens the nuts in place without hurting your hand. No sparks, and no burns. Simplifies the repair process. [How to use]: Put the bit over the screws/bolts first, Start with the lowest speed, slightly Apply pressure to remove the burr and Increase the speed as needed. Do not turn on the driver until the bit fully covers the screw/bolt. Otherwise, the bit would bump over the screws/bolts and become hard to control. [Wide Application]: Effective for hardened steel, mild steel, copper, brass, wood, fiberglass and hard plastic. Can be used on some stainless steel scews/bolts but need to be cautious. If there are noises that sounds like too difficult, then quit doing that. Tungsten Carbide Inner and Outer Deburring External Chamfer Tool Set for Removing Burr, Quick Release Hex Shank Deburring Tool for Metal Rod, Tube, Copper/PVC Pipe