<b>Replace part numbers: </b> <br> 11537541992 <br> 11537544638 <br> <br> <b>Fitment: </b><br> N54 3.0L twin-turbo motors 335i, 335xi, 135i. <br> N53 (3.0L non-turbo) 2006 - 2010 325i, 330i, 525i, 525xi, 528i, 528xi, 530i, 530xi. <br> N52 X3<br> N20 (2.0L turbo) Z4 2013 & up<br> This fitting also fits the next generation N55 motors in all chassis. <br><br> <b>Product Features: </b> <br> This product is made from high strength aerospace aluminum. <br> Also, this product was designed to maximize the resistance to breakage, so that it will not fail. <br> The coolant flow path through the center of the fitting is optimized to maximize coolant flow. <br> There are no sharp corners on this fitting so that the coolant will not be disrupted as it passes through. <br> This product is a direct replacement for the plastic fitting on BMW PN 11537541992 and 11537544638. <br> This BMW PN consists of a 25mm (1.0") hose and a plastic fitting. <br> This hose runs from the coolant thermostat housing to the front of the head. <br> The plastic fitting on this hose is a known weak spot in the coolant system as it commonly cracks and leaks. <br> Fit for 3.0L twin-turbo N54 (3.0-litre twin turbo) motors 335i, 335xi, 135i and the N53 (3.0-litre non-turbo) 2006 - 2010 325i, 330i, 525i, 525xi, 528i, 528xi, 530i, 530xi and the N20 (2.0-litre turbo) Z4 2013-, and the N52 X3. This fitting also fits the next generation N55 motors in all chassis.