1、This bike headset base is made of qualified aluminum alloy, solid, firm and durable to use, ensures a long service life. 2、Suitable for 42-52 All Hide/Large-diameter Outer Frame Headset/44-55/56mm Headset. 3、C base or D base for choosing to meet your different needs. 4、C Base for 1.5inch Taper Fork. D Base for Straight/Taper Fork 5、Great accessory for mountain bike and road bike. Features: This bike headset base is made of qualified aluminum alloy, solid, firm and durable to use, ensures a long service life. Suitable for 42-52 All Hide/Large-diameter Outer Frame Headset/44-55/56mm Headset. C base or D base for choosing to meet your different needs. C Base for 1.5inch Taper Fork. D Base for Straight/Taper Fork Great accessory for mountain bike and road bike. Specifications: Condition: 100% Brand New and High Quality Brand: RISK Material: Aluminum Alloy Color: Black Outer Diameter: C/D: Approx. 51mm / 2inch Inner Diameter: C: 39.7mm / 1.5inch D: 29.9mm / 1.1inch C Base for 1.5inch Taper Fork D Base for Straight/Taper Fork Bearing Angle: 45° Type: Open Applicable: for 42-52 All Hide/Large-diameter Outer Frame Headset/44-55/56mm Headset Weight: Approx. 7-13g Packing List: 1 x Bike Headset Base