The Crank Brothers Iodine C Directset omits the standard headset cup and replaces it with flanges incorporated directly onto the bearing itself. This lowers the stack-hieght of the Iodine C Directset to an industry best 21mm, perfect for todays long travel all mountain bikes. If you are a lite bike freak you can still keep your bike light without worrying about durability, this bad boy is one tough headset.