Once you experience the extra smooth large diameter stainless steel sealed ball bearings of the Solos bike headset you will want them in all your bikes. Stylish alloy bearing cups are CNC machined to a precise fit to keep contaminants out and the good stuff in. Cane Creek Solos Headset made of CNC-Machined aluminum cups. Sealed stainless steel cartridge bearings with low drag rubber seals. Neoprene bearing seals. Includes the Wheels Manufacturing pinch locknut, required for use on our bicycles. This special locknut allows you to make in the field headset adjustments with only a 3mm hex wrench.