1. Made of classic carbon steel material, high hardness, offer superior cutting and durable.Widely used suitable for DIY, home and general building or engineering using, etc. 2. Quickly and accurately drill a smooth hole. Better in centering and no skid.-edged chamfer design will fast discharge from the hole on both sides automatically.It can effectively prevent the accumulation of debris retention, the drilling efficiency. 3. Our Countersink drill bit sets include 3 kinds of sizes:2.8 x 8mm, 3.2 x 8mm, 3.5x 8mm, very suitable for using to multi size wood hole drilling. One tool for multi uses, your working efficiency. 4. This countersink drill set is contains 3pcs hex key wrench, the hex key to adjust counter sleeve depth and drilling depth for screws of various lengths. Complete specifications can satisfy all you demand. 5. with drilling machines with chuck, for drilling in wood or wood flooring. It is recommended to the center punch to position before drilling, keep the drill bit Vertical to prevent the drill from bending or breaking. Material:Knife head YG8 alloy, knife body 45# carbon steel, surface sprayed colour:Silver+Orange Package Contents: 3 x counterbore drills 3 x hex key wrenchs 3 x Spare screws Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.