Kit fits the below shocks but will have leftover seal depending on your compression adjuster vs climb-switch spec. See Related Products for further information on components of this kit. PDF showing contents of o-ring kit is available here
Identification: 2016-2020 Fox DHX2 are coil piggy back shocks with dual damping adjusters on the piggy back branch. Early shocks use a smaller main shaft seal, later shocks use a fatter main shaft seal.
If IFP pressure is too low the shock will cavitate and knock on fast hits as well as ingest air via the main shaft seal. If IFP pressure is too high you get extra preload force and extra seal friction.