1. Extra Long Length & 2 Types of Shanks: Extra long 300 mm body provides better stability and balance during fast operation to ensure perfect position. The groove length is 180 mm with round shank and reduced shank. 2. High Quality Material: Classic carbon steel material for fast cutting of hard wood materials. High hardness, excellent cutting force and durability. 3. Full Set of Standard Sizes: With our edited drill bits, you can process holes in 7 different diameters (Round Shank | 1/8'', 3/16'', 1/4'', 5/16'', 3/8'' Reduced Shank | 7/16'', 1/2''), perfectly meeting your different needs. 4. Brad-Point Design - Due to the sharp tip, the Brad-Point design can quickly penetrate the surface. This allows users to precisely position marks with the drill bit. Better centering and no slipping.