Womail 2PCS Grenade Alloy Valve Caps Dust Covers Bike Bicycle MTB BMX Car Purple Protective Car Tyre Valve Caps to help prevent leakage, dirt and other objects from damaging cores Weatherproof and durable Material:Aluminium and Plastic Size approx :7mm(inner diameter) x 36mm(L) Instead of the original bad caps of your tire,prevent the valve stem from leaking