N is the next letter in our A-Zdvent calendar, represented by Emeco's lightweight aluminium Navy Chair designed for use on US submarines.

American company Emeco's 1006 Navy Chair was conceived in 1944 as a strong, durable and lightweight seaworthy seat.

The designs were hand-formed from soft, recycled aluminium and welded into shape. Each product was then tempered – heated and cooled to increase strength – and finally anodised at the end of what Emeco describes as a "77-step process".

Now available in brushed or polished finishes, the Navy Chair is recognised by its simple silhouette, its trio of back-bracing elements and its indented seat.

Emeco was originally set up to develop furniture for military ocean vessels. By 1950, the brand's aluminium chairs were used to furnish many of the US Navy's ships and submarines, including the first nuclear submarine, Nautilus.

In the years after the Second World War, the US government became the largest purchaser of Emeco chairs all the way through the 1970s.

Sales of the Navy Chair plummeted when the US military was significantly downsized at the end of the Cold War.

More recently the Navy Chair's design has been the subject of legal and copying disputes.

In January last year, American company Restoration Hardwood agreed to permanently cease sales of chairs that Emeco claimed were "cheap knockoffs" of the Navy Chair, after a settlement was reached.

Online home rental brand Airbnb removed aluminium seats from its San Francisco headquarters after Emeco pointed out that the designs were knockoffs of the Navy Chair.

However, a series of new designs have been released by Emeco to compliment the original product.

Purpose-made seat pads for the chair were launched earlier this year so owners could finally avoid the shock of sitting on ice-cold aluminium.

Also this year, Japanese studio Nendo reimagined the iconic design as a range of stools and tables that Emeco launched in Milan.

A version made from recycled Coca-Cola bottles, named the 111 Navy Chair, was released in 2010.

Another Emeco chair that made it into our A-Zdvent calendar this year is Philippe Starck's aluminium Icon Chair.

Dezeen is publishing an A to Z of iconic chairs to count down the days until Christmas. Catch up with the list so far »