【Hardened Iron Material】The bicycle hollow shafts are made of high-quality iron after a quenching process, they are stronger more durable than ordinary iron. Moreover, compared with other aluminum alloy materials, it is not easy to oxidize, so driving in the rain is not a problem. 【WIDELY USED】Quick release front wheel rear hub, convenient labor-saving, suitable for bikes with axle sizes of 20/22/24/26 inch, working on 6/7/8 speed road bikes. It is the best choice for bicycle lovers. 【Size】 Front wheel short hollow shaft size: 11 cm/4.25 inches, front wheel quick release: 6 inches/6.02 inches. Long hollow axle of rear wheel: 14.5 cm, quick release of rear wheel: 19 cm, hollow axle diameter: 1 cm 【Easy to Install】 The bicycle hub set is easy to install remove without additional tools, saving time. In addition, the quick release skewer bike axle are easy to carry you can repair the bike yourself in case of emergency. 【Easy to carry】Lightweight will not add anything to your workout or long-term cycling exposure. It can be taken with you when cycling is easy to use. It is a necessary riding piece for bike maintenance, especially for mountain bike enthusiasts.