The Tekton 1/4, 3/8, 1/2 in. Drive 12-Point Socket Set with Rails (214-Piece) includes every socket in both standard and deep length from 5/32 to 1-1/2 in. and 4 to 38 mm with no skipped sizes. 12-point socket openings provide an exact fit and maximum contact with hex, double hex, and square fasteners. Radiused corners prevent fastener round-off by applying force to a fastener's flat sides, rather than its corners. Large size markings are permanently impressed into the material by a roll-stamp die and are as large as possible while still being readable along the socket's curved surface. Small deep-length sizes feature fully stepped shoulders, providing greater reach into tight, recessed areas. Detent grooves and beveled edges provide a smooth and secure connection with the drive tool. The portable organization rails have twist-to-lock clips that hold sockets securely and can be repositioned anywhere along the rail.