For tapered ZS56/ZS56 ID headtube, to suit 1-1/8” to 1.5” tapered fork. SRS routing allows compatibility with internally routed systems. SPECIFICATIONS HEADSET TYPE: Zero Stack Upper/Zero Stack Lower Cup STEERER TUBE: Tapered 11/8" to 1.5" MATERIAL: Alloy STACK HEIGHT: 17.5mm (6.5mm 11mm) UPPER CUP: 56mm Flush Cup LOWER CUP: 56mm Flush Cup UPPER BEARING: 45° x 45° 1.5" ACB Sealed Bearing 51.8mm OD 42.1mm ID - 075E LOWER BEARING: 45° x 45° 1.5" ACB Sealed Bearing 52mm OD 40mm ID - 070E WEIGHT: 139.1 grams