The MMR Performance 90mm billet coolant expansion cap for BMWs has been designed from the ground up in the UK, constructed from a solid billet of aluminium.
Each MMR cap starts life as a solid billet of 6061 aerospace-grade aluminium. It's meticulously machined from this billet with the latest CNC 5-axis technology, before being polished, then gloss-anodised to stay beautiful year after year.
All MMR coolant caps arrive pre-sealed and pre-installed with an OE spec valve and internal spring. No need to remove the valve assembly from your OE cap. A true plug and play solution.
Fits: All BMW with matching 17 11 7 639 021 OE part number