This is a set of step drills made of high speed steel 4241. Different specifications can meet different drilling requirements. The aluminum box can better accommodate and protect the drill bits.Specifications:Material: high speed steel 4241Color: yellowQuantity: 5pcsSize: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 / 0.3in3/16" to 7/8": 8mm / 0.3in1/4" to 3/4": 8mm / 0.3in1/8" to 1/2": 6mm / 0.2in3/16" to 1/2": 6mm / 0.2inPackage size: 150 * 110 * 40mm / 5.9 * 4.3 * 1.6inPackage weight: 480g / 1.1lbPackage list:5 * Step Drill1 * Aluminum Box