FSA Orbit Z 1.5R ZS Reducing Headset The FSA Orbit Z 1.5R ZS Reducing Headset features a very low-profile design primarily for mountain bikes and is compatible with Cane Creek internal style headsets (Zero-Stack). In other words, 1.5" to 1-1/8". The company's patented alignment tip affords an increased durability and performance, while the 7075 alloy crown race keeps the weight of this component low. TH brand 36 degree Micro Angular Contact Bearings (Red Seal) are used to keep it smooth. FSA Orbit Z 1.5R ZS Reducing Headset Specifications: Bearing type: Cartridge Crown race: 30 S.H.I.S lower: ZS49 S.H.I.S upper: ZS49 S.H.I.S. stem clamp diameter: 28.6mm Stack height: 17.7mm Weight: 89 grams | FSA Orbit Z 1.5R ZS Reducing Headset Black, 1.5 to 1 1/8"