This is a set of step drills made of high speed steel 4241. Different Specifications can meet different drilling requirements. Features: Made of fine quality high speed steel, wear resistant, not easy to rust, has a long service life. Double groove design for faster and smoother cutting. Different Specifications can meet different drilling requirements. Suitable for workpiece with hardness is less than 25°, such as carbon steel, iron plate, aluminum plate, pvc plate, wood board and so on. Specifications: Material: high speed steel 4241 Color: yellow Quantity: 5pcs Type: 1, 2 (optional) Size: 1/4" to 1-3/8" (10 steps): 1/4", 3/8" 1/2", 5/8", 3/4", 7/8", 1", 1-1/8", 1-1/4", 1-3/8" 3/16" to 7/8" (12 steps): 3/16", 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4", 13/16", 7/8" 1/4" to 3/4" (9 steps): 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4" 1/8" to 1/2" (13 steps): 1/8", 5/32", 3/16", 7/32", 1/4", 9/32", 5/16", 11/32", 3/8", 13/32", 7/16", 15/32", 1/2" 3/16" to 1/2" (6 steps): 3/16", 1/4", 5/16", 3/8", 7/16", 1/2" Shank diameter: 1/4" to 1-3/8": 8mm / 0.3in 3/16" to 7/8": 8mm / 0.3in 1/4" to 3/4": 8mm / 0.3in 1/8" to 1/2": 6mm / 0.2in 3/16" to 1/2": 6mm / 0.2in Package size: Type 1: 150 * 110 * 40mm / 5.9 * 4.3 * 1.6in Type 2: 90 * 70 * 70mm / 3.5 * 2.8 * 2.8in Package weight: Type 1: 480g / 1.1lb Type 2: 300g / 10.6ounce Package List: (optional) Type 1: 5 * Step Drill 1 * Aluminum Box or Type 2: 5 * Step Drill