HardDrive remote reservoir rear shocks by RacingBros' feature full adjustability with preload, compression and rebound adjusters to easily adapt to all riding styles and conditions. Whether you choose stock 12.5" length for your Dyna or Sportster, or you want the tall 14" curb hopper club style look, these performance shocks with race proven "Speed Adaptive Valving" will provide you with the ultimate ride. Speed Adaptive Valving (SAV). Internal floating piston design for consistent performance. Components made from A7075 forged aluminum then precision CNC machined. Progressive rate springs with tapered ends to avoid bowing and bottoming. Note: 2004 - 2013 Sportsters may require relocation of rear master cylinder with 14" shocks.