Under Armour typically allows customers to use multiple gift cards for a single purchase, although there may be a limit on the total number of gift cards that can be applied at one time. It is always advisable to check the current policies on their website for the most accurate information, as these policies can vary based on promotions or specific sales events. When using gift cards online, customers will generally enter the gift card numbers during the checkout process. If there are any specific terms, such as the maximum number of cards allowed or other restrictions, those details will be outlined in the appropriate section on the Under Armour website. Therefore, visiting the website for up-to-date and comprehensive details on gift card usage is recommended.