I admit I'll likely not use it anytime soon, but does anyone know how the "10% discount on in-flight duty-free" for 1Ks work? (Prior to posting, I searched here for "discount duty free" as my search terms and nothing came up.) It is listed on http://www.united.com/web/en-US/content/mileageplus/premier/default.aspx under Fee waivers and discounts, but I am curious as to how to receive the discount? Has anyone here used it? If so, do you show your 1K card and the amount is automatically taken off or something else? Maybe one day I will take advantage and I figure I might as well find out the process in advance! Thank you!