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 Introduction total length??330MM Distance between the eyes??298MM Eye Diameter(Bushing)??1/2″ Width??59MM Measure 11.75″ eye-to-eye Diameter of eye opening is 1/2″ 5 step pre-load adjustment range to help tune them for your weight Pre-load adjustment tool included Note: This product is measured by hand and may have an error of 1-3cm, which is based on the actual product. If you have any questions, please feel free to email! This type of motorcycle shock absorber is designed to reduce the vibration caused by rough roads.