Aftermarket arms may use rubber or polyurethane bushings at the frame, or some use spherical rod ends. Each has its pros and cons in use. Rubber provides the most comfort like the factory suspension, but flexes more under use, providing less precise handling. Rod ends offer greater strength and precise handling, but at greater monetary expense and increased noise transmission into the cab. Urethane bushings characteristics fall somewhere in the middle and need to be kept lubed to prevent squeaking.