Culligan OR-233 3/8" Inlet/Outlet Filter Housing O-Ring 5 Pack of the OR-233 Culligan Whole House Filter O-Rings Fits systems: SY-2000, SY-2100, SY-2300, SY-2500, SY-2650, US-600, and US-640 Will arrive with TORK Header in sealed packaging, TORK is a Trademarked Aftermarket Brand This is a Bulk Package of 5 O'rings