This Armstrong 40-155 55mm 12 Point 3/4-Inch Drive Metric Standard Socket USA is a great addition to any mechanic's toolbox. It is made by a popular brand and is designed specifically for impact use. The socket is a single item and is of standard size 55mm. The drive type is 12 point, ensuring a secure grip for any tool. It is perfect for those in the automotive industry or anyone who regularly uses hand tools.