These countersinks, made of high carbon steel, are very sharp and durable and you use them for a long time. 1/4" hex shank fits most handheld and stationary drills. Seven flute design reduces vibration for smoother drilling and extended life. Precision-ground 82 degree tip for countersinking into wood plate or thin plastic. Features: Countersink bits are made from good quality high carbon steel which ensures a long service life. Hex shank size 1/4" (6.35mm) and includes 2 cutting edges of 10mm, 13mm. Great for chamfering, deburring and countersinking. Seven flutes design provides small chip loads and quicker removal. Can discharge wood sawdust more rapidly and smoothly in the process of using. Suitable for board of low hardness such as wood, plastic and other soft material. Cannot be used for metal. Specifications: Material: High carbon steel Color: Black Cutting Edge Diameter: 10mm / 0.39", 13mm / 0.51" Hex Shank: 6.35mm(1/4") Length: 49mm / 1.93" Flute: 7 Angle: 82 Package Includes: 2pcs x Countersinks