These OEM Subaru strut top mount locking nuts hold the suspension top hat to the car. Note that tightening torque on these is quite low! Over-tightening can break the studs. Torque to 14.5 lb-ft.
Fronts are sold as a set of six
Rears are the set of four.
Full care set is all ten
Fits 2008 + Subaru Platforms