The Mul-T-Square consists of two 45° blades which slide effortlessly in an industrial strength plastic handle. Each blade is made of stainless steel for precise alignment. The 10″ (26 cm) and 14″ (36 cm) arms allow for measurement of tight fit-ups or they can be expanded for up to 30″ squaring of 90° fittings. In some instances, the 45° blades are handy by themselves for simple alignment. The blades are loosened or secured by a simple twist of the conveniently located locking knob.