Special steel spacers placed under the valve springs (or rotocaps) on Opel OHV engines to increase the rev margin against valve float by 500 rpm. This means you can rev the engine 500 rpm higher! This is because the valve springs in the OHV engine limit the maximum speed.
Article number: NK-3914010614
Fits: Kadett B, C, D, E, Manta/Ascona A, B, Olympia A, Corsa A and Opel GT