CHROME VANADIUM STEEL- High strength drop forge chrome vanadium steel with heat treatment for torque, strength and durability DURABILITY- Durable black phosphate coated provides superior corrosion resistance LASER ETCHED SIZE- High visibility laser-etched markings, easy to read, quick identification and easier socket selection PROFESSIONAL- Heavy duty 1/2 inch drive deep impact sockets, size from 3/8 up to 1-1/4 inch for professional user OUTSTANDING QUALITY- The socket meets or exceeds ASME specifications with sturdy tool box for easy storage and portability