Features: As Balls retainers for Bicycles movement transmission system service. This kind of Balls bearing steel Balls inlaid in the retainer designs, It is a bicycles part, suitable for replacing the handset bearing of the bicycles. This Balls bearing retainer make of Carbon Steel, strtong, Enduring and highly intensity. Suitable for ordinary bicycles, mountain bikes, stretch bicycles. Easy and convenient to use. It is a great replacement part for bike. Specifications: Materials: Carbon Steel Model: B01C1/B01D1/BG01E1/BG01E2/B01A1/B01A2/B01A3/BG01A4/BG01B1/BG01B2/BG01B3/BG01B4 Size: as shown in the picture Package Includes: 8pcs Bike Headset Bearing note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.