1.The bearing is made of quality steel material, anti-rust, sturdy and durable 2.Fine machining ensures sleek surface and smooth rotation, fits perfectly with your bike headset 3.The sealing ring is good for keeping dust and water away to lengthen the durability 4.Built-in grease in the slot can prevent the balls from corrosion and make them rotate freely 5.Useful accessory for replacing old headset of bike Features: The bearing is made of quality steel material, anti-rust, sturdy and durable. Fine machining ensures sleek surface and smooth rotation, fits perfectly with your bike headset. The sealing ring is good for keeping dust and water away to lengthen the durability. Built-in grease in the slot can prevent the balls from corrosion and make them rotate freely. Useful accessory for replacing old headset of bike. Specification: Material: Bearing Steel Color: Shown as picture Options: 41mm; 41.8mm; 47mm; 49mm; 52mm Size(Outer/Inner Diameter): Approx. 41/30mm; 41.8/30mm; 47/ 34.5mm; 49/38mm; 51/40mm; 52/41mm Weight: Approx. 21-32g Suitable for Repair most of the full hidden, semi-hidden and external bearing headset on the market. Note: Unable to repair old loose ball or ball (like bearing) headset. Package List: 1 x Bike Headset Bearing