The Park Tool OBW-3 is a specialty wrench designed for the installation and adjustment of side-pull and dual-pivot rim brakes. Its unique offset design and thin profile (2.1 mm thick with 6.5 mm fingers) allow it to access tight places where standard wrenches would be impractical.
The OBW-3 features a 14 mm open-end wrench and a spring holder tool for engaging the brake tension spring that is accessible on some side-pull brake calipers.