Designed to fit into a zero stack (44mm ID/50mm OD) head tube, but allow the use of a tapered steer fork. Description and Materials - ACB with Forged alloy upper cup - ACB with Forged alloy lower cup - Stainless steel crown race Sizes - For 1-1/8" to 1.5" tapered steerer Finish - Black FSA part number 101-1321A Not sure if this is the one you need? Check out the handy FSA Headset ID Tool here http://www.fsaeasyheadset.com/