Our house-owned fully integrated headset set made by Acros, with double sealed stainless steel industrial ball bearings. Fits all frames with standard IS41 / IS52technical details:Material: Aluminum, stainless steel (ball bearings)Type: fully integrated (IS)Fork steerer: 1 1/8"S.H.I.S.: Top IS41/28.6 - Bottom IS52/40Press-in dimension Ø: Top 41 mm / Bottom 52 mmBearing: Industrial - angular contact ball bearing, double sealed