A set of fitting aids to enable the operator to correctly fit the Teflon seal (or ring) onto a BMW fuel injector prior to refitting the fuel injector to the cylinder head. Engine codess: N13, N14, N18, N20, N26, N43, N53, N55, N63, N74, S55, S63, B38, B48.The set brings together the two OEM fitting aid sets: 13 0 190, 13 0 280. The Teflon seal material is designed to expand once installed into the injector bore to enable an effective seal. Two different methods of shrinking the Teflon seal, depending on the engine code reference and the type of injector fitted.