16-inch & 19.2-inch stud centre markings simplify framing jobs Three-rivet corrosion-resistant hook moves for accurate insideoutside measurements Secure blade lock wont creep during measurements 7-foot standout Easy readability with -inch wide blade Entire blade coated with Mylar polyester film for added durability Heat-treated spring stands up to repeated use Special Tru-Zero hook does double-duty as a pivot for drawing circles & arcs