Chrome Molybdenum Alloy Steel for exceptional strength and long lasting durability. High visibility laser etched markings with additional hard stamping on the opposite side. Surface drive technology. Pin hole available for use with pin and o-ring for secure socket retention. Sockets come packaged in a reinforced molded case with sizes marked for quick identification and storage Case has reinforced steel hinges and buckles for added durability, security and strength. Set includes: SAE Standard sizes: 3/16" - 9/16"; Metric Standard sizes: 4mm - 15mm; SAE Deep sizes: 3/16" - 9/16"; Metric Deep sizes: 4mm - 15mm.