RockShox Air Top Cap The RockShox Air Top Cap is a factory replacement part for select RockShox forks equipped with an air spring. Whether you are refreshing the appearance of your fork or are looking to replace a cap that was damaged, this cap is easy to install so you can get the fork back up and running. Features: Includes full top cap assembly For fixed travel air spring fork models with 32mm stanchions Uses a lockring tool to remove/install top cap into fork Specifications: Compatibility: 2020+ SID B1 | SID B4 |Reba A7 | Reba26