This is a bottle of Yokomo #450 Shock Oil. The number represents the viscosity of the oil. The higher the number, the higher the viscosity and the more damping your shocks will have when riding over bumps. The thickness of Yokomo shock oil is measured using the more linear Europen Centi Poise "Cps" system, which is different to the "Weight" system used by Team Losi and Team Associated in the USA. Please use the pull down menu to pick the oil weight.