MR121 | Headset Bearing | By FSA | AKA: TH870E

From FSA:

• Inner x Outer x Depth (mm): 30.5 x 41.8 x 8
• Inch Dia: 1-1/8”
• Angle / Chamfer (Deg): 45 / 45
• Bearing ID: 30.5mm
• Bearing OD: 41.8mm
• Bearing Thickness: 8.0mm
• Internal Angle: 45 Degrees
• External Angle: 45 Degrees
• Material: Bearing Steel
• Seal: Double-sealed 2RS