It is a plastic card, credit card size with a barcode on it. You scan the card and 10% comes off the top. If you use the regular checkout they scan the card, 10% off the top and usually they say thank you for your service. My daughter has used the card too. Someone said Home Depot gives a discount but my understanding is that they only do that at veterans day but I may be wrong.
Yes, I get it's a credit card size or keychain thing, but if I carried one of those for each and every store I ever shopped at, I'd need a dolly to carry my wallet / key chain.
And I believe the official Home Depot policy is only for Veterans day, but they often will give you a discount, but ring it up as some other discount to get around not having the full time Veteran discount. But I have had them tell me no before.