RockShox Reverb Stealth Dropper Seatpost - 30.9mm 100mm BLK Plunger Remote C1RockShox Reverb Stealth Dropper Seatpost 30. 9mm 100mm Black Plunger Remote C1. The Reverb C1 Stealth offers new travel options and an overall shorter post length allowing more riders to benefit from longer travel options. Our new Vent Valve Technology allows for an easy on the bike solution to the squish of the past. The ALL new Reverb Stealth is here. Features Vent Valve Technology for super simple service if the need arises Shorter overall post