Pressure can be adjusted by springs and air (nitrogen). The eye of shock has tensile strength more than 2000kgf. The dumper and spring designed for long durability. The point of performance and price comfortable,stable, high quality,high-performance motorcycle parts. Fitting manual is not included. installed by qualified mechanic is recommended. Color: Black+Gold 370mm (14 5/6″) total length 340mm (13 3/8″) eye to eye Eye Diameter: 12mm Eye thickness : 21mm Spring thickness: 7mm Spring Width(approx): 60mm Pressure can be adjusted by springs and air (nitrogen) Package included: 1 pair Shock Absorber Fitting manual is not included. installed by qualified mechanic is recommended. Notice 1.Please allow 1-3mm error due to manual measurement.Pls make sure you do not mind before you bid. 2.The color may have different as the difference display,pls understand. This type of motorcycle shock absorber is designed to reduce the vibration caused by rough roads.