Description of Atoplee Nitriding Black Spiral Fluted
{Good Quality Metarial} Made of HSS 4242,high hardness,strength and longevity. {Design}Shank: hex shank;Groove: spiral ; Surface treatment: Nitriding black. {Size}Shank diameter: 6mm;Step quantities:5/ 9 /15 steps;Step diameter:001 :4, 6, 8, 10, 12mm ; 002 :4, 6, 8, 10, 12, 14, 16, 18, 20mm;003: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32mm. {Usage}Used with pistol drill or bench drill, water it to cool while working to prolong its life, the proper drilling speed is 250-400 rpm.Suitable for these work-pieces that hardness is lower than 25 degree and the thickness is beyond 4mm, such as aluminum parts, insulation board, PVC plate, etc. {Package Included}3x HSS Hex Shank Nitriding Black Spiral Groove Step Drill Bit.