Park tool offset brake wrench obw3as a manufacturer of bicycle specific tools since 1963 you can safely rely on park tools many years of experience the worlds largest bike tool manufacturer is the first choice of professional and home bicycle mechanics around the world features unique design offset wrenches which allows them to be used in tight places such as centering caliper brakes obw 3 has a 14mm opening and the other end fits into the tension springs to rotate the brake on its boltbu