A 60mm outside diameter polyurethane bush, the larger of the two poly bush sizes we stock. It suits bigger bracket bores and larger-bodied pumps and canisters, cushioning them so vibration is damped rather than transmitted straight into the mounting point. Beyond the mechanical benefit there is a practical one: an isolated pump is markedly quieter in the cabin, which matters on a road car where a high-flow pump bolted rigidly to the boot floor turns the whole body panel into a speaker. Polyurethane holds up well to fuel and oil exposure, so it will not perish and go soft in the way a natural rubber isolator does. Measure your bracket bore to confirm fitment.