Made of high material for durability and stability Pressure can be adjusted by springs or air (nitrogen); Operation of the coil- over springs and air cylinder is helpful to reduce the shock No instruction included, professional installation recommended The suspension leg provides a smoother ride and better shock absorption management. The spring seat is insulated from the spring to ensure a quiet and comfortable ride The suspension shocks struts provides a smoother ride and better overall damping management Specifications: Color: Black 350mm( 13 3/4″) total length 320mm( 12 5/8″) eye to eye Eye Diameter: 12mm Eye thickness : 21mm Spring thickness: 7mm Spring Width(approx): 60mm(2.4″) Max loading: <;= 300 kgs Pressure can be adjusted by springs and air (nitrogen) Package included: 2pcs Shock Absorber Note: This product is measured by hand and may have an error of 1-3cm, Due to the screen and lighting configuration, the colors may be slightly darker or lighter. This type of motorcycle shock absorber is designed to reduce the vibration caused by rough roads.