Genuine OEM Toyota Water Bypass Hose No 1, part number 16261F2270. This hose is a critical component of the engine's cooling system, designed to bypass certain areas of the engine or radiator under specific temperature conditions to ensure optimal engine warm-up and operating temperature. Its precise dimensions and material composition are engineered to resist heat and coolant degradation. Genuine OEM ensures the correct flow path and durability for efficient engine cooling.