Many people join Costco so they can fuel their car cheaply and save money on items like groceries and paper towels. But one of the best — and least obvious — deals at Costco is the store’s selection of gift cards. If you’ve never purchased a gift card from Costco before, here are three important things to know.

1. Costco gift cards are discounted

The main benefit of purchasing gift cards from Costco is that you can purchase them for less than face value. Here are some of the fantastic restaurant gift card deals Costco is offering today (November 6):

• $100 TGI Friday Gift Cards for $79.99
• $75 Subway Gift Cards for $59.99
• $100 IHOP Gift Cards for $79.99
• $100 Domino’s Gift Cards for $74.99

But it’s not just restaurants where you can buy gift cards. Costco also sells gift cards for entertainment venues like bowling alleys and movie theaters, among others. It’s worth browsing the store or looking online and seeing what additional deals catch your eye, especially as the holidays approach.

You can find a larger selection of options at Costco.com. And many of the site’s gift cards can be delivered to you electronically so you receive them immediately.

2. They cannot be returned

Costco’s return policy is one of the most generous on the market. You can generally return almost any item at any time and for any reason.

But gift cards are one of the few Costco purchases that can’t be returned. Once you buy one, you’re stuck with it. For this reason, be careful when buying gift cards from places you don’t usually go.

For example, Costco currently sells $100 Dave & Buster’s gift cards for $79.99. You might think it’s a good deal to grab because your kids love going there. But if the closest one is 90 minutes away and you haven’t been to Dave & Buster’s in a long time because of it, your $100 in gift cards could be sitting unused in your wallet.

3. You can earn 2% on gift cards with an Executive Membership

The benefit of upgrading to an executive membership at Costco for $130 per year (compared to $65 for a basic membership) is earning 2% cash back on your purchases. And that extends to gift cards. If you spend $79.99 on a $100 gift card, not only do you save $20, but you also earn $1.60.

Plus, if you use the right credit card to purchase your gift cards at Costco, you can earn additional rewards that will put more money in your pocket. Click here for a list of the best credit cards for Costco shoppers.

Costco gift cards are one of the store’s best, lesser-known deals. It pays to take advantage of the discounted prices and cash back. But be sure to only buy gift cards that you know you’ll use. Otherwise, instead of saving money at Costco, you might end up wasting money and ending up with gift cards that do you no good.