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 Sockets 6 Piece 1/4" Drive Deep External Torx® Socket Set includes E4, E5, E6, E7, E8, & E10 Sockets packaged on a clip rail.