A pillar box is a type of free-standing post box. They are found in the United Kingdom and British overseas territories, and, less commonly, in many members of the Commonwealth of Nations such as Cyprus, India, Gibraltar, Hong Kong, Malta, New Zealand and Sri Lanka, as well as in the Republic of Ireland. Pillar boxes were provided in territories administered by the United Kingdom, such as Mandatory Palestine, and territories with agency postal services provided by the British Post Office such as Bahrain, Dubai, Kuwait and Morocco. The United Kingdom also exported pillar boxes to countries that ran their own postal services, such as Argentina, Portugal and Uruguay. Mail is deposited in pillar boxes to be collected by the Royal Mail, An Post or the appropriate postal operator and forwarded to the addressee. The boxes have been in use since 1852, just twelve years after the introduction of the first adhesive postage stamps (Penny Black) and uniform penny post. Mail may also be deposited in lamp boxes or wall boxes that serve the same purpose as pillar boxes but are attached to a post or set into a wall. According to the Letter Box Study Group, there are more than 150 recognised designs and varieties of pillar boxes and wall boxes, not all of which have known surviving examples. The red post box is regarded as a British cultural icon. , Royal Mail estimates there are over 115,000 post boxes in the United Kingdom. Construction Most traditional British pillar boxes produced after 1905 are made of cast iron and are cylindrical. Other shapes have been used: the hexagonal Penfolds, rectangular boxes that have not proved to be popular, and an oval shape that is used mainly for the large "double aperture" boxes most often seen in large cities like London and Dublin. In recent years boxes manufactured in glass-fibre or acrylonitrile butadiene styrene (ABS) plastic have been produced that do not follow these general outlines. These are for use in secure indoor locations such as supermarkets. Cast iron pillar box construction comprises three distinct main parts: The cap sits on top of the carcass and is usually bolted down from inside. Some designs after 1965 do not have a separate cap. Caps can also be fitted with a separate bracket, normally of cast iron, which supports a Post Office Direction sign (POD) indicating the nearest Post Office. The door contains