Evotech oil filler caps are machined from aluminum billet using sophisticated CNC machineries. We created these with a hexagonal head in order to help avoid someone stealing your oil cap. In fact it is necessary to have a particular key to open the cap. Some holes have been made around its shape for fixing safety wire which is required during competitions. The 6 milled pockets and the 6 holes give our oil caps lightness but without reducing its strength. For the assembling simply use a hexagonal key or better pawl keys.