Sized for 0.127" (3.23mm) nipples, the same size as the Park Tool SW-2 (red) spoke wrench, this SW-40 at first glance looks like the three-sided interface of the SW-0. On closer inspection you can see two hardened lip edges that grasp the fourth side of the spoke nipple for greater leverage, power and control without risk of stripping the nipple. This does require the user to slide the tool down the spoke over the nipple and fit it onto the nipple, which can slow you down a little, but when the spoke nipples are frozen, softer alloy, or already show signs of edge wear, the SW-40 will get the job done.

The precision-sized spoke wrench is made of hardened tool steel and nickel-plated for long service of daily use. Park coats the loop shape handle with the same black vinyl of the SW-0, but adds blue bands at the bottom of each side of the loop for easy recognition.