Pair of Bitubo WMB0 rear shock absorbers with adjustable spring preload. Born for the world of Harley Davidson, Modern Classic and Custom, the WMB Bitubo shock absorbers have specific calibrations for each motorcycle model. They improve driving comfort and control of the motorcycle thanks to the internal hydraulic system and the springs which, depending on the vehicle, can be linear or progressive. The spring preload is entrusted to a threaded ring that allows a much more precise calibration of the rear of the bike. The shock absorbers are single chamber pressurized by nitrogen gas with floating piston. The body is in high-strength alloy steel while the heads are in CNC machined aluminum alloy. The product is supplied with specific assembly instructions for the motorcycle model, suspension manual and key for adjustments. Specific for: Harley Davidson FXDBP Dyna 103 Street Bob 2013>2017.