"Blue for metric and red for SAE so technicians can spot the right size instantly and work more efficiently","Manufactured from high-grade, impact resistant, heat-treated steel","Mid-length Chrome Sockets with high-visibility color-impregnated laser-etched markings","The Opti-Torque feature applies torque to fastener sides, not corners, while Counter-Torque helps distribute the torquing stress uniformly throughout the socket 3/8" DRIVE 9/16" SAE 6 POINT MID-LENGTH CHROME SOCKET BI186 | Matco Tools