Designed with the professional in mind. Secure lock helps prevent blade from creeping during measurements. Includes 16" and 19.2" stud center markings to help simplify framing jobs. Special Tru-Zero hook does double-duty as a pivot for drawing circles and arcs. Three-rivet, corrosion-resistant hook moves for accurate inside/outside measurements. High-visibility yellow steel blade remains rigid up to 7 ft. and is coated with MylarÂ® polyester film for long-wearing durability. Extra-tough chrome case with heat-treated spring that stands up to repeated use. Belt clip makes portability easy.