Internal components for servicing the Reverb and Reverb Stealth mechanism. Seals the upper tube from the inner shaft as it cycles Fits A1-A2 generation externally routed Reverb seatposts For "A1" designated posts, 2010-2012 A1 posts have a silver return speed adjuster on the remote and no laser etched logos on stanchion by the saddle cradle For "A2" designated posts, 2013-2016 A2 posts have a black return speed adjuster on the remote and no laser etched logos on stanchion by the saddle cradle