This is a Genuine OEM DCT transmission oil cooler for the F10 M5, F06 M6, and F12/F13 M6. BMW used this endurance-spec cooler on the M4 GT4 race car for better cooling and can be used on the M2/M3/M4 S55 cars as an aftermarket track upgrade. As it is located in front of the radiator it does make it very exposed to road/track debris so owners should be mindful of this.
However, the larger fin density requires more airflow to get the cooling benefit so it's not recommended for daily stop-and-go driving.
For the S55 engined cars this works out at a 30% increase in core size and a 18% increase in front surface area compared to the OEM DCT cooler.