Features The force is in a plane, which is effectively protected and can avoid the situation of bursting at the beginning. Universal shank type, the drill tail adopts a roun designed, which makes the clamping more stable. U‑shaped chip grooves, facilitate the discharge of wood chips and improve drilling efficiency. With overall heat treatment, making it has high hardness and long service life. Wide application, suitable for square hole drills and square tenon machines. Specification:Condition: 100% Brand New Item Type: Square Hole Drill Bits Material: Bearing Steel Color: As picture shown Uses: Suitable for wood products such as density board, medium fiber board, particle board, wood, etc., suitable for square hole drills and square tenon machines Specification: 1/4, 5/16, 3/8, 1/2SpecificationHole  SizeShank  DiameterGrooves  DepthTotal  Length 1/46.4mm / 0.3in4.1mm / 0.2in 45mm/  1.8in170mm / 6.7in  5/168mm /  0.3in5.5mm / 0.2in 60mm /  2.4in200mm / 7.9in  3/89.5mm /  0.4in6.5mm / 0.3in 60mm /  2.4in210mm / 8.3in  1/212.7mm /  0.5in8.5mm / 0.3in 60mm /  2.4in210mm / 8.3in Package List:4 x Square Hole Drill Bits Note:Cannot be used on metal, concrete, glass and gypsum board. Package List 4 x Square Hole Drill Bits