AIRTEC Motorsport Focus Mk3 Rear Diff CoolerAIRTEC Motorsport rear diff cooler. Designed to lower temperatures of the rear differential, AIRTEC Motorsport are proud to offer a rear diff cooler for the Mk3 Focus RS. With the rear differential on the new Mk3 Focus RS already proven to be a weak point from factory, causing warning lights to display the AIRTEC motorsport diff cooler is a must have part for your Focus RS. This diff cooler used original mounting holes and comes pre drilled ready to