The side curtain airbags of the Mini Countryman is now being produces by Key Safety Systems based in Detroit, USA. Mini has chosen Key Safety Systems for the job because of their cold gas technology — a system that deploys argon and helium to inflate the curtain. This technology is beneficial because the cold gas inflator provides more consistent cushion stiffness and deployment times than pyrotechnic inflators. Thus, this increases the safety of the Mini Countryman.
Source: Autonews