The Kodlin Lowering Kit lowers the rear of HD M8 Softail models up to 1 ?" (40mm). *Plug and Play*! The kit is easy to install and does not require shortening of the threaded rod or to send the suspension out for final assembly. It includes new pre-installed bearings and installation instructions. 880-4030 for all M8 Softails WITH pre-load adjuster knob (FLHC/FLHCS Heritage Classic, FXBR/FXBRS Breakout, FLFB/FLFBS Fat Boy, FLSB Sport Glide, FXBS/FXFB Fat Bob, FLDE Deluxe, FXDR 114) 880-4031 for all M8 Softails WITHOUT the pre-load adjuster knob (FXBB Street Bob, FXLR / FXLRS Low Rider / Low Rider S, FLSL Slim, FXST Standard)