Features: Made of High quality for Cr-V steel with high hardness, good toughness and corrosion resistance; Mirror polished surface, not easy to rust, long service life. The spring loaded brake ball of the adapter firmly locks the socket to prevent sliding. Common size combinations multiply the range and capability of your socket system making your set very versatile with multiple repair need-s. 1/4 inch (hole) to 3/8 inch (for head), 3/8 inch (hole) to 1/4 inch (for head), 3/8 inch (hole) to 1/2 inch (for head), 1/2 inch (hole) to 3/8 inch (for head), 3/4 inch(hole) to 1/2 inch(for head), 1/2 inch (hole) to 3/4 inch (for head). Widely used in industrial, mechanical or construction projects. Specifications: Material: for Cr-V Size: 1/4 in 3/8 in 1/2 in 3/4 in Package Includes: 6x Socket Adapter 1x Storage Box note: Please allow 1-3cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item.