*using the black spacer
When you tighten or snug down the cap for the shock cartridge you can experience a small amount of binding on the shaft .

This binding is due to the black spacer is a bit off spec in size and even can have a small amount of flash .

White spacer is molded just right , the material also made of a Teflon base plastic and will bring a smoother shock with less striction.

* can feel the improvement off & on the track running the car.