Description Reviews Supertech Valve Guides are precision-machined from high quality Magnesium Bronze material. These guides will fit the intake & exhaust on the MINI Cooper & Mini Cooper S (R55, R56, R58, R59, R60, & R61). They will fit a standard 5mm valve stem. Pair these in combination with low friction nitrated valves to provide the best solution for performance and durability. Don't forget to add valve seals! Note: Sold as a set of 8. You will need 2 packs to do all 16 valves.