The Tekton SHA21124 1/2 Inch Drive x 18 Inch Extension is a single item hand tool designed for automotive use. With a drive size of 1/2 inch, this extension allows for reaching into tight spaces to access nuts and bolts. The manufacturer, Tekton Tools, ensures quality and reliability in this product. Additionally, this product carries a California Prop 65 Warning, indicating it may contain materials that could be harmful if ingested or otherwise come into contact with the skin.