... square, most popular screwdriver bits 33pc screwdriver bits setincludes:(7) Security Screwdriver Bits #T8, T15, T20, T25, T27, T30, ... T40 (6) SAE Security Hex Screwdriver Bits #5/64, 3/32, 7/64, 1 ... /8, 9/64, 5/32 (6) Metric Security Hex Screwdriver Bits #2, 2.5, 3, 4, 5 ... Bit Holder Comes in a convienient storage case All security screwdriver bits are made of chrome vanadium