【Dimensions】This ball bearing bike fork has outer diameter: 40mm/1.57"; inner diameter: 33mm/1.30", each cage has 20pcs 4mm balls for replacement bike parts. 【High Quality Material】Metal. Made of metal, high quality, durable and high strength. 【Package includes】30 bicycle ball bearings, enough for your daily use, a must-have for cycling enthusiasts. 【Lightweight and portable】The storage earpieces are light and easy to carry, and the packaged cycling accessories can be replaced at any time. 【Suitable for most bicycles】This bicycle bearing is suitable for mountain bikes. Outer diameter about 40mm Inner diameter about 33mm The most popular mainstream ball holder for mountain bike front fork shells