Editing Preferred number (section)

==Retail packaging==
In some countries, consumer-protection laws restrict the number of different prepackaged sizes in which certain products can be sold, in order to make it easier for consumers to compare prices.

An example of such a regulation is the European Union directive on the volume of certain prepackaged liquids (75/106/EEC<ref name="EEC_106"/>). It restricts the list of allowed wine-bottle sizes to 0.1, 0.25 ({{frac|1|4}}), 0.375 ({{frac|3|8}}), 0.5 ({{frac|1|2}}), 0.75 ({{frac|3|4}}), 1, 1.5, 2, 3, and 5 litres. Similar lists exist for several other types of products. They vary and often deviate significantly from any geometric series in order to accommodate traditional sizes when feasible. Adjacent package sizes in these lists differ typically by factors {{frac|2|3}} or {{frac|3|4}}, in some cases even {{frac|1|2}}, {{frac|4|5}}, or some other ratio of two small integers.