The durable bits found in this screwdriver set are made from high-grade tool steel hardened to 56-58 Rockwell C. A custom-molded box houses the contents of the set which includes: - Kit Includes: - 2 ergonomic driver handles for delivering maximum torque - 54 hollow ground bits specifically designed to match the thin slots in gun screws sizes ranging from approximately .120 x .020 to .360 x .070 - 8 Allen bits (1/16 5/64 3/32 7/64 1/8 9/64 5/32 3/16) - 4 Phillips bits (#0 #1 #2 #3) - 3 Torx bits (T10 T15 T20) - Includes two each of the very thinnest bits in this set this is intentional as the thinnest are most likely to break