Sizes are marked both with a high-visibility laser marking and a permanent stamped marking that won't wear off, 12-point opening fits double hex (12-sided), hex, and square-shaped fasteners, Radiused corners prevent fastener round-off by applying force to a fastener's flat sides, rather than its corners, Meets a minimum of 1.3 times the ANSI/ASME standard for proof torque, Twist-to-lock socket rail organizes and securely holds sockets in place, both for in your toolbox and on the go.