Patented bit holding system forces bit surface to opposing side for maximum bit retention - strengthPackaged in patented impact resistant "slide rail" system Heat treated socket bases for durability and service abilityChrome sockets; S2 and alloy steel bitsIncludes E4, E5, E6, E7, E8, E10, E12, E14, E16, and E18 Torx® Sockets10 Piece External Torx® Set (1/4", 3/8" & 1/2" Dr.) includes E4, E5, E6, E7, E8, E10, E12, E14, E16 and E18 Torx® Sockets packaged on a clip rail.