The Matco Tools 2-pc Extra Long Double Box Flex Head Ratcheting Wrench Set, No. SRRFXLM22T, features a patented design of box end that is intended to open and fasten even a 50 percent rounded off screw. Its 90 teeth are designed to provide high torque, requiring only 4 degrees of movement. The wrenches' long reach bodies allow the user to access narrow and deep spaces. Featured in this wrench is a chrome-vanadium material which provides a heat treatment process as well as durability and additional strength.