Our products are made by high-qualified materials with technology and the advanced computer numerical control processing. Pressure can be adjusted by springs and air (nitrogen) The is strictly monitored by standard to make sure the excellent performance and the good condition in the long-term use. The point of performance and price comfortable,stable,high quality,high-performance motorcycle parts If you want more eye diameter size copper rings please click those photos. Product Name:Motorcycle Shock Absorber 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 Package included:2pcs Shock Absorber NOTE: The eye of shock has tensile strength more than 2000kgf. The dumper and spring designed for long durability(mor than 1 million) This type of motorcycle shock absorber is designed to reduce the vibration caused by rough roads.