Plastic Cover for Thunderbolt/Display Port Input

Good morning everyone. You know those little plastic caps that cover male end of your display port or thunderbolt adapters? The one I had for my Ethernet adapter disappeared somewhere in the house. Been googling on where to buy one and I keep getting those port covers for the actual Macbook. Where can I buy a cap or do I need to just buy another adapter and hope I don't lose the cap again?

Thank you.