Unique design structure: This is a multi-purpose self- adjust double heads ratcheting wrench. Two specifications: Spring-loaded jaw works on any 9mm - 45mm (5/16 - 1 3/4) nuts, 6 and 8 sided bolts, round bolts and even pipe.Convenience for everyone to do work. Easy to use: It can apply the maximum strength force & torque & protecting the surface of nuts at the same time in both loosen or fasten situations. Widely used: It also applies to maintenance of vehicles such as bicycles, automobiles, motorcycles and so on. High quality: Made of high carbon steel, durable for long time using.