RealWheels RW0020VSB-2 Rubber Valve Stem Stabilizers for Aluminum Wheels - 2-Inch are designed to help prevent damage to extensions caused by rubbing against the wheel. Worn extensions can lead to air leakage and result in tire damage. They feature easy installation - simply align stabilizer with the extension and push into the cutout. They fit aluminum wheels with 2 and 2.2-inch hand holes. Each stabilizer is made of thick Buna rubber.