This headset design is what Chris King® built it's reputation on. The sealed bearing cups paired with a precision-matched adjusting and lock nut set could outlast a bike frame.
The 2Nut™ features stainless steel sealed bearings housed in aluminum upper and lower cups. The adjusting nuts and lock nuts are also made of aluminum.
The 2Nut™ headset is recommended for anyone using a threaded fork and quill stem in combination with headset spacers and/or a cable hanger, and is a popular headset for cyclocross.