The NTN Timing Belt Kit - 137766 is a comprehensive set of products designed to service the timing belt of a car. It includes a timing belt, tensioner, and idler pulley, all essential components for maintaining the proper function of the timing belt. The timing belt is responsible for synchronizing the rotation of the engine's camshaft and crankshaft, ensuring the smooth operation of the engine. The tensioner and idler pulley help to keep the timing belt taut and in place, preventing it from slipping or becoming loose. This kit is suitable for various car models and is an essential maintenance item for ensuring the longevity and performance of a vehicle's engine.