Wheel adapter: made of superlight and ultimate strong 6061-T6 or 7075-T6 heat-treated aluminum, which would be the best material for the adapter.The wheel adapter have CNC-machined holes and are hub centric for the hightest level of accuracy. They are designed to fit tight to your hub while centering your wheel. This prevents vibration when spacing or adapting the wheel.The most important part of wheel adapter is high-strength wheel studs. Wheel studs is our star products. We always choose the best material and best production process. All wheel studs are made of SCM435 or SCM440, mechanical performance can be 10.9 Grade and 12.9 Grade.