If you are fitting a GMC227 stepped-bore tandem master cylinder to a left-hand drive (LHD) classic Mini built before May 1985, this kit is required. It connects the replacement master cylinder to the firewall mounted PDWA valve, and must be installed differently than the original pipes. Pipes will come with correct length and fittings but will need to be bent by installer. Fittings are metric on both ends. Ref: BAU5655, LK17049, SSB77049.