The definitive industry standard for this style of tool is the Park Tool CCW-5 Crank Bolt Wrench, a dual-sided, heavy-duty workshop tool engineered specifically for 3-piece bicycle cranksets. Its core feature is a 14mm thin-walled socket on one side and an 8mm hex wrench on the opposite side, allowing it to easily service both traditional square-tapered axle bolts and modern splined configurations.