Dobinsons Spring & Suspension polyurethane bush kit Replaces OE bushes with high quality polyurethane for maximum vibration dampening and best cabin comfort. Bushes have unique internal diamond grease traps to maximize bush life and reduce squeaking or noise. These replace the OE bushing, or the bushing that is supplied with some leaf spring manufacturers which are prone to squeaking. Kit contains bushes, for the fixed end and both shackle ends of each leaf spring. Only one kit is required per vehicle. Grease injected into the pin will push grease between the outer edge of the bolt and the inside of the bushing, and also around the outside flange between the bushing and the spring hanger. This provides maximum lubrication and resistance to any friction, as well as eliminating any noise. This design of bushing will hold grease for longer than usual. Incorporating a recessed twin hole greasable design to ensure both halves of the polyurethane bush receive even grease distribution. Greasing polyurethane bushes not only reduces friction and wear, it also reduces the chances of corrosion on the shackle pins and reduces squeaking.