Forged from the finest chrome molybdenum alloy steel-the best choice for strength and durability Radius corner design-to extend the life of fasteners The design drives the side of the fastener instead of the corner Provides increased strength, but also avoids rounding of rusted or damaged fasteners 1/2-Inch drive, 21mm, universal impact socket, Weight: 0.55 Pounds, Manufacturer: Sunex International