Every now and then, you’ll find a blank red Tab: a red Tab with nothing but the trademark symbol on it.
Since the Tab device is one of the world’s most frequently copied trademarks, it requires some extra moxie on the part of LS&Co. to protect the company’s exclusive legal right to market clothes with the Tab. It’s therefore necessary to produce a certain percentage of Levi’s® products with a plain Tab with only the ® symbol on it. This shows that LS&Co. owns trademark rights in the Tab itself, not just the Levi’s® wording trademark.
Rest assured; the blank red Tabs are authentic Levi’s®.