If the size/item you're looking for is out of stock, you'll see a blue button that says "Notify When Available." Please click that button and enter your email so we can send you an alert when the product is back in stock!
P.S. If there's a "sold" watermark on the product photo, that product is completely out of stock. If you're unable to add your selected size to your cart, then that specific size is out of stock.