The FSA SX Pro No.55 Semi Integrated Headset is for tapered 50mm/61mm OD head tube with forged alloy and CNC machined upper and lower cups.1.1/8" / 1.5", 36°×45° ACBFor tapered 50mm / 61mm OD head tubeFor 1.1/8" to 1.5" tapered forkForged alloy upper...
Headset MY13 SIRRUS/VITA HEADSET INTEGRATED LOWER/EXTERNAL UPPER BLKS132500006
The United Supreme headset follows the same path as the rest of the line. Two precision sealed 45° x 45° bearings encased by 7075-T6 alloy top cap and variable 5mm & 2.5mm spacers, so you can adjust that front end to just how you like it....