RUIMI Titanium Step Drill Bit Spiral Metric Sizes 3Pcs (Step Bits 3/16'' - 3/4") TITANIUM | HIGH SPEED STEEL: classic high speed steel with titanium coating for proven capability SPLIT POINT TIP | increases cutting speed with self-centering and prevents walking Spiral Flute DESIGN | clears chips faster and allows particles to escape easily Hex SHANK | fits into power tools chuck securely and eliminates slip INCLUDES 10 STEP SIZES | 1# 4-32mm 2# 4-20mm 3# 4-12mm 3 piece fractional, titanium coated Step Drill Bit set tools. Step bits are a powerful ally in the workshop. Combining up to 13 drill bit sizes in one unit you can spend more time working on your project than swapping out drill bits. The Dual Fluted design helps keep the work area clean with improved chip removal and the cutting angle of the bits keeps your holes smooth with minimal de-burring required. 4241 high-speed steel, used in hardness under 25  workpiece, the plate thickness under 5 mm. such as carbon steel plate, sheet iron, insulation boards, wood. Cannot be used for stainless steel. When inject cold water while working, can effectively extend the service life of the drill bit. These Step Drill Bits are ideal for variety of materials from metal, plastic, fiberglass to wood They also help to enlarge existing holes The two flute design tips made the penetration faster without chipping Due to the difference between different monitors, the picture may not reflect the actual color of the item. Please understand, Thank you. 3pcs Drill Bits 3/16&#034;, 1/4&#034;, 5/16&#034;, 3/8&#034;, 7/16&#034;, 1/2&#034; 1/4&#034;&#039;5/16&#034;, 3/8&#034;, 7/16&#034;, 1/2&#034;, 9/16&#034;, 5/8&#034;, 11/16&#034;, 3/4&#034; 1/8&#034;, 5/32&#034;, 3/16&#034;, 7/32&#034;, 1/4&#034;, 9/32&#034;, 5/16&#034;, 11/32&#034;, 3/8&#034;13/32&#034;, 7/16&#034;, 15/32&#034;, 1/2&#034;