Chase Bays Reservoir Covers are designed to help to prevent spill over of vital fluids in spirited driving. Even in the rare situation that the caps are jarred open, the tank covers help contain the spill and minimize fluid loss or mess. The tank covers also prevent dust and debris from accumulating on the tanks and potentially contaminating the fluid. Best of all, they keep your reservoirs warm if they are chilly. Reservoirs have feelings too! The reservoir covers are sold individually.