RockShox Dropper Post Bushings & Inner Sealhead O-Ring Description: The RockShox Dropper Post Bushings & Inner Sealhead O-Ring work together to minimize the play in your seatpost. When you are servicing your Reverb dropper seatpost, installing these factory replacement parts will ensure your post is in its optimal working condition. Features: Includes 10 separate bushings and O-Rings for servicing the inner sealhead for a Reverb dropper seatpost. Fits B1 generation Reverb and Reverb Stealth dropper seatposts. B1 posts have a black return speed adjuster on the remote and "ROCKSHOX" laser etched logos on stanchion by the saddle cradle