Service kit to assist in scheduled maintenance and/or rebuild of RockShox dropper seatposts.Includes Blue 1-Piece U-Cup Seal Internal Floating Piston (IFP)Requires RockShox Specialty Tools to perform Service: Post Bleed Tool, Oil Height Tool, IFP Height ToolB1 posts have a black return speed adjuster on the remote and "ROCKSHOX" laser etched logos on stanchion by the saddle cradleRebuilds IFP, Poppet, Seal Head, Dust Seal, Piston, Brass Keys and Bushing