The Fox Fork Seal Kit keeps newer (2016+) Fox 32/34 or 36/40 Forks with the Fit4 damper running smoothly on the trail. The seals in this kit are an important first line of defense from the flinging muck and fine dust that accrues on your fork stanchions during rides. FOX recommends replacing them at every service interval, so you can reap the benefits of a smoothly operating fork without stiction inhibiting small-bump sensitivity.