Used to rebuild and replace all seals on the Fox 36 air shafts with the NA2 design. Fits all 36 forks with NA2 air shaft including Factory, Performance Series Elite, Performance Series and Rhythm. Also fits Marzocchi Bomber Z1 air shaft. Recommended replacement intervals from Fox = 125 Hours Install with Fox 20wt Gold Oil and suspension grease like Slickoleum Tools required to replace all air shaft seals: 803-01-324 - Fox GRIP Damper Body Clamps (Soft Jaws) 398-00-657 - Fox NA2 Bullet Shaft Tool If you have a fork older than MY2017 and you aren&';t sure if you have an NA2 air shaft, you can enter your fork&';s serial number into the Fox Product Search Database.