FSA's core line of headsets that have become an industry benchmarkAll Orbit headsets feature forged and CNC machined 6061 T6 alloy cups
Orbit IS CF Z ZS X MX XL II include angular contact bearings
Orbit Xtreme Pro include stainless steel industrial cartridge bearings and stainless crown race
Orbit UF include lower angular contact bearing and upper 5/32 inch caged bearing
Orbit DL include 5/32 inch caged bearings
IS: 36x45 degree Cane Creek Integrated CF: 45x45 degree Campagnolo Integrated ZS: ZeroStack shallow Z: ZeroStack deep or Xtreme
Pro X MX XLII UF DL: External Cup traditional available for 1 inch 1
1/8 inch tapered and 1.5 inch applications
For clarification go to http://www.fsaeasyheadset.com