This kit contains enough parts to install six injectors. This installation kit includes the o-rings, dust seal, and washer gaskets needed to install the injector. It includes three different sizes of nozzle washers to accommodate the various injector tips. The thin (1.5mm) 7mm inside diameter nozzle washers is used in all early B series engines(except 1991 automotive) and C series engines. The thick (2.5mm) 7mm inside diameter nozzle washer is used in 91 B series application. The 5mm inside diameter washer is used in later B & C series engines.