Mivec Tappet Lock Nut - Mitsubishi FTO 2.0 V6 Mivec Models|
There are 24 of these (Price is for ONE) They are the ones that lock the Mivec Tappet in Place and can be damaged quite easily as they are thin and it's easy to round the hex off
Exploded Diagram Showing Location Fitted HERE
Mitsubishi Part Number MD206828