To apply the coupon code, select the products you'd like to purchase and add them to cart.

On the website, click on the Cart button on the upper right side of the website page: 
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You will see the Cart Drawer and at the bottom of the cart drawer, you will see the Discount or Gift code field: Type your discount code and click on "Apply" 

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When you click on the check out button on the cart drawer (see above screenshot). 
You will be routed to the Cart Page: 

You will see the Discount or Gift code field below the Subtotal details: Type your discount code and click on "Apply" 
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Please be sure to enter your coupon code accurately, as it is case-sensitive. Happy savings!