The corners of this revolutionary wrench head act like spring hinges to grab and tighten around the rounded, chewed-up, corroded, worn, and/or under-sized hex surfaces of brake and fuel fittings. The design of the XForce Tools Flexforce Wrench allows easy access to tight areas where most brake and fuel fittings are found and flare nut wrenches won't reach. The 'Spring-Torque' provides tighter grip on the fitting with increased force on the wrench. Capable of up to twice ANSI standards. The 4-pc wrench set fits the fittings of more than 90 percent of domestic and import vehicles on the market.