21mm Torque-Tight™ loose lug nut indicators are used in some applications in class 1, and 2 trucks. Class 1 and 2 trucks are commonly thought of making frequent stops throughout its work day and with Torque-Tight™ installed a driver can visually check their lug nuts through the duration of their day.
Torque-Tight™ indicators are a small plastic piece that is cut to a teardrop shape, then a 24 point section of teeth are cut to in the shape of a circle that create an interference fit on a standard Hex Nut. Torque-Tight™ indicators are designed to be much larger (more than 2x in fact) than our competitors, this allows for a blatant visual reference when performing a walkaround. Our Torque-Tight™ indicators come in 3 standard colors, Green, Orange, and Black, however they are available in any color you can imagine (with a minimum order). For less than $25 you can reduce the risk of wheel off accidents, and heck, you may even save a few lives in the process.
Vehicles that use 21mm:
Here is a list of the known vehicles that use 21mm lug nut indicators.