I was considering buying the pass, but I want to know if it is something that is permanently attached to a car or something that can be carried on my person. I think it may be a wallet card, but I can't tell.
Let's assume I'm buying it online.
It is a physical card, around the same size as a credit card.
On the back is a space for 2 signatures. The person using the card must be one of the two people that has signed the card, and you need to show additional ID (eg, a drivers license) to prove that.
When you purchase it they will punch a hole in the card to set the expiry month, with the expiry year printed on the card itself.
If you are 62 or older AND are an American Citizen or permanent resident, you should get an America the Beautiful SENIOR pass. It is $10.00 and is lifetime.
Read details at https://www.nps.gov/planyourvisit/passes.htm