13 Series O/R shocks contain Freon cells for fade-free performanceSame features as the standard 1200 Series, but set up for the special demands of dual-sport and off-road ridingHeavy-duty spring is recommended for riders over 200 lb. , passenger usage over 50% of the time and/or add-on accessories of considerable weight.Standard spring is recommended for bike as sold new, excluding any accessories, rider weight under 200 lb. and passenger use limited to under 50% of the time.EU: Standard spring is recommended for bike as sold new, excluding any accessories, rider weight under 90,72 kg and passenger use limited to under 50% of the time.EU: Heavy-duty spring is recommended for riders over 90,72 kg, passenger usage over 50% of the time and/or add-on accessories of considerable weight.