115 Pieces Set Includes: 29pcs Fractional Size: 1/16 to 1/2 inch bits in 1/64th increments; 26pcs Letter Size: A To Z; 60pcs Numbered Size: #1 To #60; Set includes the drill bit holder with size index for easy storage and organizing. Perfect Drill Bits: Precision grinding process for a clean surface and high grinding accuracy. Universal round drill shank, widely applicable of tool holding systems and tightly clamped. 135° Split Point & Twist Design: The 135 degree fast cutting point is automatically centered and penetrates quickly with less pressure, reducing walking, fully ground drill bit with sharp and durable cutting edge. Twist design for clear chips faster. Enhanced M35 Alloy Material: These drill bits contain 5% Cobalt alloy steel, which increases wear resistance and durability. Industry grade HSS M35 drill bit set, harder than HSS 4241 used in other similar drill bits set. Professional After-Sales Service: The outer box for stepped drill bit is sturdy and easier to carry and store.