Description The Park Tool Four-Sided Spoke Wrench (SW-40) is your solution for wheel building using 3.23mm wrench flats. This spoke wrench uses the same world famous design and high quality materials as our three-sided spoke wrenches, with a unique four-sided wrench design for extra strength and support to help prevent slipping and deformation of nipples. Each SW-40 is made in the USA, and is heat treated and nickel plated for long service. Park Tool spoke wrenches are vinyl dipped to indicate the size at a glance. Park Tool Four-Sided Spoke Wrench SW-40 features & specs Sized for spoke nipples with 3.23 mm (0.127″) wrench flats Equivalent to Park Tool SW-0 This size is often found on higher-end bikes Typical compatible nipple brands include DT Swiss, Sapim, Wheelsmith, Pillar, and many others — always measure to be sure. Grabbing this spoke wrench to true a wheel? Park Tool have a great instructional video on the process.