1: Suitable for Aluminum, insulation board, PVC board chamfer,steel, aluminum, sheet metal, carbon steel, 304 stainless steel, etc.2: Made of high speed steel material, 4241.3: 118 X Bit Design, you can drill from any angle, no slipping.4: Triangle , fit for most drill chuck and no slipping.5: Can drill 5mm thickness material.One drill bit contain lots of sizes diameter.These Double-Fluted Step Drill Bits faster cutting and drilling than single flute bits. The easy-to-read step markings and targets save time when drilling holes. Thick 3/8inch hex provides a , positive grip and 't spin out in the drill.Two cut faster and keep bit coolerFast-starting, non-walking drill tipHigh-visibility silver targets for primary hole sizesThick 3/8-Inch hex 't round out in the drill chuck for a more positive grip3 hole sizes(7/8,1-1/8,1-3/8)High-visibility silver targets for primary 19 hole sizes; come with 19 sizes (3/16inch, 9/32inch, 3/8inch, 7/16inch, 17/32inch, 5/8inch, 11/16inch, 25/32inch, 7/8inch, 29/32inch. 31/32inch, 1inch, 1-1/16inch, 1-1/8inch, 1-5/32inch, 1-7/32inch, 1-9/32inch, 1-5/16inch, 1-3/8inch) so you can drill up holes with different diameters, saving your time and efforts to change bits.These Double-Fluted Step Drill Bits faster cutting and drilling than single flute bits. The easy-to-read step markings and targets save time when drilling holes. Thick 3/8inch hex provides a , positive grip and 't spin out in the drill..Colour:Photo ColorMaterial:high speed steelPackage Contents:1 x Drill bitOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.