Park Tool Four Sided Spoke Wrenches use 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 aluminum nipples. Each Park Tool SW-40 & SW-42 is made in the USA, and is precision-stamped, hardened and nickel plated for long service. Park Tool Spoke Wrenches are vinyl-dipped to indicate the size at a glance. The SW-40 is sized for 3.23mm (0.127") nipples. These nipples are often found on higher-end bikes. Typical compatible nipple brands include DT Swiss, Sapim, Wheelsmith, Pillar, and many others. The SW-42 is sized for 3.45mm (0.136") nipples. This size is often found on most department store bikes, as well as many other low-to-midrange bikes. Always measure to be sure.