Yakamoz 3PCS High Speed Steel HSS Titanium Step Drill Bit Set Quick-change 1/4" Hex Shank SAE - Total 28 Sizes 3-piece step drill bit set includes three standard SAE step drill bits that replace 28 individual drill bits 3-Piece Set with Quick-change 1/4" Hex Shank: 3/16" - 1/2" (6-Step), 1/4" - 3/4" (9-Step), 1/8" - 1/2" (13-Step) Two-flute design provides faster, smoother cutting without walking and a tri-flat shank ensure a firm grip Ideal for variety of materials from metal, plastic, fiberglass to wood Made of super strong M2 steel with titanium coating for added durability and bit life