The online boutique 3floz.com is meeting a need that came out of the Transportation Safety Administration’s travel ban on liquids that are more than three ounces. Launching in January, the boutique offers well-heeled travelers luxury beauty and grooming products in packaging that’s, well, three fluid ounces or less. Though TSA-compliant, the downsized products can also be shipped to consumers’ hotels ahead of their arrival. Why brands should care: Is there an opportunity to more tightly position existing offerings to meet a new need?