Made From Chrome Molybdenum Alloy Steel (Cr-Mo) for Exceptional Strength and Durability. Off-Corner Loading Design for Reduced Fastener Rounding. Black Oxide Coating for Corrosion Resistance. Parallel Neck Down Design On 8, 9, 10, 11mm Standard and Deep Sizes for Improved Access to Restricted Fasteners. High-Visibility Laser Etched Markings for Quick Size Identification. Secondary Hard Stamping. Includes Blow Mold Case With Reinforced Steel Hinges and Steel Buckles for Strength and Security.