XZN, also known as the triple-square drive system essentially overlays 3 squares over one another to give you driver teeth that have a 90-degree angle. This drive system can also be used with a standard square Robinson driver if no other option is available. XZN fasteners are typically used where high torque is needed - usually specific areas in a car - and are often found in German vehicles like BMW, Volkswagen, Porsche and Mercedes to name a few. Given the specialty use of the triple-square for German automobiles, it makes sense that Hazet and Stahlwille are the primary makers of XZN screwdrivers and bits, but you can also find some made by Wiha too.