The Grey Pneumatic 1010FP 3/8″ Drive x 5/16″ Square Female Pipe Plug Socket is a fastener drive bit designed for automotive use. With a standard (SAE) measurement and a size of 5/16 inch, this socket is perfect for removing and installing fasteners with ease. Made by the manufacturer Grey Pneumatic in China, this high-quality tool is a must-have for any automotive mechanic or DIY enthusiast. Additionally, it comes with free express shipping in the United States, making it convenient and efficient to have on hand for your next project.