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 1/16" - 1/4" Bit Sockets 10 Piece 1/4" SAE Hex Bit Socket Set includes: 1/16" - 1/4" Bit Sockets packaged on a clip rail.