Collapsible double -end back -up wrench

The utility model belongs to the mechanical tool technique relates to a collapsible double -end back -up wrench. The length of back -up wrench commonly used is fixed, and two kinds of specification wrench ends can be used at most in both ends. Its shortcoming is because the length of back -up wrench is longer, not only inconvenient with carry and deposit, because the wrench end at both ends is fixed, consequently often there is the one end spanner circumstances about not using even commonly used in unable smooth use the in narrow and small space simultaneously in addition. The utility model provides a back -up wrench that the length of spanner handle can be stretched out and drawn back to conveniently adjust the length of the arm of force.