Product Details: Update your semi truck with quick and reliable steering, with the Donaldson P550637 Power Steering Filter that ensures you're Ready for the Road Ahead™. Due to its spiral filter, this replacement device is able to help deliver reactive steering by capturing contaminants in the power steering fluid that could cause damage to the system. Built with durable materials to offer a long service life. FleetPride is your First Click in Heavy Duty®.