This is a 75 ml bottle of Ultimate Racing 550 cSt silicone shock oil used with oil filled shocks. Ultimate Racing shock oil is made from 100% pure silicone oil and will not thin out in hot weather or thicken up in cold weather. The higher the viscosity number of the oil, the thicker the oil is. Ultimate Racing silicone oil content antifriction additives to ensure shock absorbers useful life and minimize viscosity changes.