The Starrett Combination square features a square head made from durable 11H cast iron, designed for precision and reliability. The square head includes a reversible lock bolt, a built-in scriber, and a spirit level (except for the 4" model) to enhance its functionality. The hardened steel, photo-engraved blade ensures long-lasting accuracy, making this tool ideal for various measuring and marking tasks in both professional and DIY applications. Black wrinkle head finish