1、High Quality: Made of high quality iron material, it is wear resistant, durable, not easy to deform, and can be used for a long time. 2、Improve Stability: Balance the inner and outer bearings of the pulley to reduce the shaking of the bearing and wheel, improve the stability, and then increase the speed and reduce the bearing loss. 3、Easy Installation: The installation is simple. Place the bearing sleeve in the middle of the two shafts to keep the bearings perfectly parallel. 4、Prevent Bearing Explosion: It can position the inner ring of the bearing and effectively prevent the bearing from bursting. It is suitable for the installation of most sliding wheel bearings on the market. 5、Stable Performance: Professional manufacturing, craftsmanship and high accuracy help to provide stable performance to meet your various needs. Item Type: Skateboard Bearing Spacers Material: Iron Weight: Approx. 114g / 4.0oz Height: 10.6mm / 0.42in Inside Diameter: 8mm / 0.3in Outer Diameter: 10mm / 0.39in 40 x Skateboard Bearing Spacers