The .006 General Purpose Fine Wire Stripping Wheel is sold singularly and 4 are required for use in the PD9. All of our Wire Stripping Wheels are manufactured in house to ensure the highest standards of quality and delivery. We make stripping wheels to fit all competitive machines as well as for all Eraser Models. We can also manufacture custom size wheels. There are many factors that determine the proper grade of wheel for a specific wire stripping application. These include wire size, type of insulation, strip length, and number of wires stripped at one time. For this reason, we suggest you give us a call, to determine the proper grade for your application.