Suits: Nissan GU Patrol with ZD30 Common Rail engine 2007 on.
This oring is located near the top of the injector, as pictured in a 2nd photo.
It seals the injector to the metal plate at the top of the injector to secure it in place.
Injectors themselves do not normall give troubles on these engines, but the seals can leak.
Any questions, please let us know.
Injector is not included in the sale, only the large oring.