Fire eye iris fit 15 is4252 headsetfire eyes love for bikes can be seen in the quality and design philosophy they put into making every fireeye frame and component not only do they think hard about how to make a framecomponent better they try and do it with some style features material aluminum 6061 top 1 18 fully integrated headtube inner diameter of 41 8mm bottom 1 12 fully integrated headtube inner diameter of 51 9mm surface finish anodizedmanufacturing process full cnc m