It is a common feature of most tax systems that taxes are not raised on goods to be exported. To do so could place the goods at a disadvantage to those from other countries, for example if the tax rate in the territory of sale is higher than the tax rate in the territory of consumption. Either the tax system allows the goods to be exported without taxes (stored prior to export in a bonded warehouse), or taxes can be claimed back when they are exported (see VAT). Such exemption also applies to goods supplied for use on ships and aircraft, because they are consumed outside the country. Businesses supplying such goods can do so tax- and duty-free. Goods sold to passengers on board ships or aircraft are tax free. The passenger can either consume them on board, or import them tax-free into the country they are traveling to, so long as they are within the traveler's duty-free allowance. Most tax regimes also allow travelers entering a country to bring in a certain amount of goods for personal use without paying tax on them, the so-called "duty-free allowance"; because it is not economically justifiable to collect the small amounts of tax involved, and would be an inconvenience to the passengers. A duty-free shop works under the same system. The goods must be exported intact (they cannot be consumed in the country of sale), and they are importing into the destination country under that country's own tax rules. In some countries, in order to ensure that goods are exported intact, they are hand-delivered in a closed bag to the passenger at the gate after their ticket is scanned. In the United States, duty-free shops are technically considered class 9 Bonded Warehouses with regard to the U.S. Customs & Border Protection: Class 9. Bonded warehouse, known as duty-free stores, used for selling, for use outside the Customs territory, conditionally duty-free merchandise owned or sold by the proprietor and delivered from the Class 9 warehouse to an airport or other exit point for exportation by, or on behalf of, individuals departing from the Customs territory for destinations other than foreign trade zones. Pursuant to 19 U.S.C. 1555(b)(8)(C), Customs territory, for purposes of duty-free stores, means the Customs territory of the U.S. as defined in 101.1(e) of this chapter, and foreign trade zones (see part 146 of this chapter). All distribution warehouses used exclusively