Features: _x000D_Drill bit is made from carbon steel and countersink is made from good quality 45# steel which ensures a long service life. _x000D_Combined drill bit and countersink bit is great for drilling, chamfering, deburring and countersinking. _x000D_There are 10 sizes of 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 7mm, 8mm, 10mm and you can choose the one you need._x000D__x000D_Five flutes design provides small chip loads and quicker removal, it can discharge wood sawdust more rapidly and smoothly. _x000D_Suitable for drilling holes on board of low hardness such as wood, plastic and other soft material._x000D__x000D__x000D__x000D_Specifications: _x000D_Material: Carbon steel(drill bit), 45# steel(countersink) _x000D_Countersink Flute: 5_x000D__x000D_Drill Bit Diameter: 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 7mm, 8mm, 10mm, 3-10mm(3/4/5/6/7/8/10mm), 3-6mm(3/4/5/6mm)(Optional) _x000D_Countersink Diameter: 15.8mm _x000D_Hex Key Size: 55 x 20mm _x000D_Quantity: Your choice _x000D__x000D__x000D_Package Includes: _x000D_1pc(or 1 set) x Countersink Drill Bit _x000D_1 x Hex Key _x000D__x000D__x000D_Note: There are only 7pcs in 3-10set, and only 4pcs in 3-6set. 1Drill bit is made from carbon steel and countersink is made from good quality 45# steel which ensures a long service life 2Combined drill bit and countersink bit is great for drilling, chamfering, deburring and countersinking 3There are 10 sizes of 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 7mm, 8mm, 10mm and you can choose the one you need 4Five flutes design provides small chip loads and quicker removal, it can discharge wood sawdust more rapidly and smoothly 5Suitable for drilling holes on board of low hardness such as wood, plastic and other soft material