Fierce - 608 Lightweight Precision Spacers
The standard length of bearing spacers is 10.11-10.33mm and will work with most wheels. Most inline speed skaters choose to use the standard length to ensure they have "free spin".
If you notice a clicking sound as you skate, this is indicative of a spacer that is slightly longer than necessary. The clicking may only be coming from some of your wheels.
Fierce Spacers are machined with ultra precision to the .000mm ensuring an exact fit with the individual hub of your wheels.