Patented bit holding system forces bit surface to opposing side for maximum bit retention - strength. Packaged in patented impact resistant "slide rail" system . Heat treated socket bases for durability and service ability. Chrome sockets; S2 and alloy steel bits. Includes E4, E5, E6, E7, E8, E10, E12, E14, E16, E18, E20, E22 and E24 Torx Sockets 13 Piece External Torx Set (1/4", 3/8" and 1/2" Dr.) includes: E4, E5, E6, E7, E8, E10, E12, E14, E16, E18, E20, E22 and E24 Torx Sockets packaged on a clip rail