Product Feature: 5pcs Step Drill Bit in 50 Sizes: It's can work as 50pcs twist drill bits. Convenience,step drill allows to cut several holes with one drill easily without changing bit constantly. High Speed Steel: Made of super strong HSS steel for added durability and bit life. Double Cutting Blades and Three-sided Shank: Five standard HSS step drill bits with a two-flute design for faster, and 3-sided shank design prevents drill bits from slipping, smoother cutting. Widely Application: The step drill bits can be used to chamfer, bur, and drill or enlarge holes. The step drill bits can work with stainless steel sheet, aluminum alloy, plastic material and wood. (the board must be smaller in thickness than the height of step drill bits) Product Specification Type: Step Drill Bit Material: H.S.S. 4241 Length: 57~77mm/2.25~3.03in Color: As the picture shows #1 (6 steps): 3/16"" to 1/2"" (3/16'', 1/4'', 5/16"", 3/8'', 7/16'', 1/2''). #2 (9 steps): 1/4"" to 3/4'' (1/4'', 5/16"", 3/8"", 7/16"", 1/2"", 9/16"", 5/8"", 11/16"", 3/4""). #3 (10 steps): 1/4"" to 1-3/8"" (1/4'', 3/8"", 1/2"", 5/8"", 3/4"", 7/8"", 1"", 1-1/8"", 1-1/4"", 1-3/8""). #4 (12 steps): 3/16"" to 7/8"" (1/4'', 5/16"", 3/8"", 7/16"", 1/2"", 9/16"", 5/8"", 11/16"", 3/4"", 13/16"", 7/8""). #5 (13 steps): 1/8"" to 1/2"" (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''). Package Included 5 x Step Drill Bit