Description Reviews Supertech MINI Cooper Valve Keepers! Supertech provides the best solution for both performance and improved durability valves but it uses a single grove keeper. This keeper will lock your valve in place with stock or Supertech valve springs. These are 5mm 7 degree locks, sold as a set of 32 that is enough to do all your valves in 1 car. We sell intake and exhaust valve separately but we recommend buying a whole kit , N14 or N18.