Specially shaped and sized for specific bicycle jobs, especially on brakes Park CBW-1 Open End 8mm & 10mm Bicycle Brake Combo W OBW-3 Park Tool Park Tool Brake Spanner Wrench - OBW-3 - $12.99 Multitool Bike We call these Park Tool's offset wrenches because of their unique design, which allows them to be used in tight places, such as centering caliper brakes One end features a 14mm opening, and the other fits into the tension springs to rotate the brake on its bolt Park Tool OBW-3 Offset Brake Wrench - 14mm Design allows this tool to be used in tight places, such as centering caliper brakes.