Rubber seal ring inside to reduce air leak and prevent dust and dirt getting into the valve. The dust-proof tire caps are sealed completely, can prevent water, dust or sand coming into the tire, thus prolonging the tire service life High-quality material of aluminum alloy, higher Strength & Heavy-Duty Durability. Easy to install, simple screw onto the car wheel air valve.It's direct replacement, no modification needed just remove your cap and add it. Special Gift Purchase! Get an Awesome Carbon Fiber Cover for Steering Wheel Sticker as a Bonus Item after you Purchase over 45 Dollars in your next order.