Cane Creek External Cup EC34 headset. Top stack height 16mm, bottom stack height 12mm, stem clamp 28.6, tube diameter 33.95 (both top and bottom).
Constructed of 6061-T6 aluminum, Cane Creek 10 Series headsets are engineered in their factory in Fletcher, NC and are backed by a 1 year warranty. Compatible with 1 1/8″ threadless headtubes and forks. Will NOT work with Integrated or ZeroStack frames or forks.