The rear differential is a expensive part to replace, so it is important to keep differential oil temperatures cool for a prolonged life. Under harsh conditions like autocross or track racing, your differential fluids heat up and start to break down. The Perrin WRX R160 Rear Differential Cover is designed to keep these fluids at a safe temperature with enlarged cooling fins to dissipate heat. It is constructed of heat-treated cast aluminum, and will hold 30% more oil than your stock rear differential cover. The Perrin WRX Rear Differential Cover is a great upgrade for the weekend racer, and anyone looking to add some style to their WRX.