The Speedline Sealed Bearing Integrated Headsets are some of the best on the market. They are designed for the "Campy®" style of Integrated head tubes.
1 1/8" Pro Headsets are Typically used on Expert XL, Expert XXL, and older style Pro Frames , or Any Frame that you wish to use a 1 1/8" Fork and Stem on.
The Speedline headsets start with a high grade tool steel ACB ( Angular Contact Bearing ) sealed bearings with precision ground hardened steel balls. What does that mean to you? Probably not much, except that you know the bearings will last you a long time and they will spin nice and smooth.
Add on a nice CNC'd Aluminum top cap, a thin rubber dust seal to maintain the life of the bearings. The Bottom Aluminum race is split to allow ease of installation and removal.