The Nissens Automatic Transmission Oil Cooler - 90658 is a heat exchanger designed to cool the automatic transmission fluid in a vehicle. It is made of high-quality materials and has a compact design for easy installation. The cooler helps to maintain the optimal temperature of the transmission fluid, which is essential for the smooth operation and longevity of the transmission. It is compatible with a wide range of vehicles and is a reliable and durable solution for keeping the transmission fluid cool.