●Excellent performance: the headphone seal has smooth edges that do not accumulate dust or rot due to oxidation and do not strain your bike. ●High quality – bicycle headset seal made of carbon fibre, high temperature resistance, good impact resistance, matte surface, fine texture, durable, ●Advantages: more corrosion resistant than aluminium alloy seals, harder, lighter and easier to transport or install. ●Widely used: the inner diameter is about 28.6 mm and the outer diameter is 34.9 mm. For 1-1/8 inch (28.6 mm) bicycle bars, suitable for most bicycles, road bikes, mountain bikes, MTB, BMX ●Multiple thicknesses – there are 6 sizes: 2 mm / 3 mm / 5 mm / 10 mm / 15 mm / 20 mm, you can choose different sizes or make a variety of combinations to adjust the height of the handlebar, so you can be more precise height adjustment