Fsa xtreme pro is41 upper headsetthis headset features a hard wearing aluminium top cover construction, which makes it ideal for everything from clocking up the miles on your road bike to shredding the trails on your mountain bike. Fsa has also equipped this model with robust stainless steel bearings, so you can enjoy a durable, smooth action as you conquer every journey. Engineered for performance, this versatile headset weighs in at only 52.5g. This means that you'll also benefit from its incredible strength and smooth rotating performance, without worrying about adding any unnecessary weight to your ride.features top cover material aluminium bearing materialstainless steel use road, mtb fsa headset category premium fork steerer compatibility 1 1 8 tapered forks upper 36° 45° acb grey seal higher quality seals laser etched graphic to easily identify the headset spec plus provides a higher quality look for 45mm od head tube is41 30 part number 121 0010000013 weight 52.5g approxbuy fsa components from chain reaction cycles, the world's largest online bike store.