PS, Model 444 shock set. 13". Super Heavy Duty, Black

444 series shocks:
Comes with FST (Frequency Sensing Technology) which dynamically adjusts damping, according to road surface. Top mount threaded hand adjustable preload.
Note: Optionally available is 704545 for an optional QPS (Quick Preload System) adjustment kit. It replaces the stock upper shock caps of all 444 & 944 series Touring shocks, allowing quick preload adjustment without removing the saddlebags.

What are Progressive Suspension's 'Heavy Duty' shocks?
If you are a lightweight rider with a lightweight passenger, STD Duty is probably your best choice, heavy duty shocks will give you a harsh ride. For Big Guys & Gals with a lot of baggage, Heavy Duty springs are the way to go. Heavy Duty is not better, it's different.
Heavy Duty shocks or springs are recommended to be used on motorcycles that are operated at or near the manufacturers maximum load rating over 50% of the time. In short: Standard is good for combined rider weights up to 250 lbs / 113kg), Heavy-Duty (250 lbs / 113kg to 350 lbs / 159kg) and Super Duty (350 lbs /159kg and up).