Standard Steel Springs in a wide variety of spring weights and travel. The 35 mm/1.385" Internal diameter also fits DVO, MRP and X-Fusion shocks.Spring markings: 550 x 2.80All standard FOX steel springs are black and are marked with their spring rate in lbs/in (in 50 lb increments) and the total travel of the spring itself*IMPORTANT - FOX standard black springs should only be paired with shocks having less travel than the travel marked on the spring itselfUltra-durable black powder-coat finish provides protection and keeps the spring looking goodItem SpecificationsI.D. (mm)35.200000000000003MaterialSteelSpring Weight550Stroke (ins)2.264 - 2.55 FOX Steel Rear Shock Coil Spring Rear Shock Spring UPC: 821973501550