Box Two™ Integrated Headsets feature an aluminum top cap, CNC-machined bearing cover, and split crown race with super-smooth rolling, precision bearings. The 1.5-inch headset is designed solely for tapered frames and forks but also includes an adapter which allows you to run a straight 1 1/8-inch fork in a tapered head tube. It has a 45x45 degree upper bearing and a 36x45 degree lower bearing.