In the past few years it has become increasingly popular to wear your watch - particularly if it is a vintage military style - with the nylon wristband known as a Nato Strap. Technically speaking these were originally made to conform to the British Ministry of Defence Standard (or DefStan) 66-15.
Members of the military refer to them as G10s after its requisition form's reference number but the better-known moniker came about because it has a Nato stock number (NSN) on the strap. The original spec was a strap 280mm long, 20mm wide (now 18mm - and in case you're wondering all Nato armies use the metric system, even the Americans) and 12 heat-sealed adjustment holes plus chrome-plated brass fittings.
Today, these are supplied to the MoD by the Cabot Watch Company of Mile End, London. It was originally designed so that it could to be worn over or under clothing such as a flight suit or wetsuit and to keep the buckle away from the underside of the wrist, supposedly to prevent it catching on clothing - or weapons. The fact that the strap goes under the case also means that if one spring bar breaks the watch will still be attached to the wrist.
The original spec came in just one colour (Admiralty Grey) though today you can find any colour you wish, including versions in regimental or college colours. As a piece of movie legend, Sean Connery wore a tri-strip Nato strap as James Bond in Goldfinger ensuring that forever after it would have serious cred.
Watch pictured from Francisandgaye, from £16.99.http://www.francisandgaye.co.uk/