This listing is for a pair of hood hinge repair kits for Peterbilt 359 trucks. Made in the USA by Energy Suspension from their premium Hyper-Flex polyurethane formulation. Replaces Peterbilt p/ns 13-03318 and 13-03440 HYPER-FLEX The X-Treme Duty Polyurethane! HYPER-FLEX is Energy Suspensions unique and technically advanced chemical formulation performance polyurethane. It is used on all of Energys products. Some that have been awarded 9 U.S. Patents. HYPER-FLEX polyurethane provides longer component life (3 to 10 times over rubber), cutting the cost of vehicle operation! Clearly, durability is superior to most rubber components that are used for trucks and service vehicles? of all classes. HYPER-FLEX replacement polyurethane components stand up well to contaminants that often destroy rubber and have been engineered to give longer-lasting performance and not compress permanently. Road salt, oil, and a host of other common under car contaminants will eventually destroy the rubber bushings on your vehicles, not to mention the weight and torque forces that typically compress most rubber permanently! HYPER-FLEX is offered in a variety of durometers (firmness or softness), depending on the a particular product application on a vehicle. Performance tested, its used for all of Energys products?giving a higher level of performance and durability!