A NATO strap (also called G10) is a nylon loop strap with two pieces passing below the watch.
In 1973, the British Ministry of Defense released standard 66-15 for “Strap, Wrist Watch”. Soldiers could fill out Form G1098 (“G10”) and request the new-style strap for their watches.
The MoD strap was made in Admiralty Gray, 20 mm wide, and featured two chrome plated keepers and a matching buckle. There were two lengths of nylon attached to the buckle. One passed through the lugs of the watch and ended at a chrome keeper. The other, longer part passed under the watch and lugs, through this keeper, and the buckle. This kept the watch in place on the strap and also served as an extra point of attachment should one of the lug spring bars fail. Subsequently, many military-issue watches featured fixed or soldered lug bars rather than spring bars.
In subsequent years, the MoD modified the standard to reduce the width of the strap to 18 mm and specify stainless steel hardware. Some regiments have also issued straps in their regimental colors.
Since the UK is a NATO country, that organization issued a NATO Stocking Number for the watch strap and other militaries began using it. Since then, it has become known as a “NATO strap”.
NATO straps are popular on dive watches, field watches, and fliegers. Many companies today ship NATO-style straps as OEM with such military-styled watches and they are popular third-party add-ons as well.
- The Fascinating and Humble History of the NATO Watch Strap, Gear Patrol, December, 2017