OE valve stem caps?

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2014 CX-5 Touring
Our 5 came with what look like large silver-colored valve-stem caps, with a little gasket inside of them. I've never seen valve stem caps like that before. They're pretty substantial as far as valve stem caps go. Problem is that I only have 3 of them. FL tire has no cap. Maybe I could get one from the dealer where we purchased the car (used) this week?

Are these special caps related to the use of nitrogen in the tires? I thought those were usually green. I don't plan on keeping nitrogen in the tires on this car. I have a constant supply of compressed air in my garage and check and adjust tire pressures regularly in both cars, so I don't see any point in using "special air" in tires.
 
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