It's always a good idea to have some spare Traveller Schrader Valve Cores on hand. After all, these valve cores are essential for cars, trucks, lawn mowers, ATVs and UTVs. It's their job to allow air to enter and exit the tire, as well as to hold air in. These spare Schrader valve cores are tire sensor safe and compatible with standard Schrader valve stems. Sold in sets of 4.