Armies use smaller scales still. The US Army specifies models of the scale 1:285 for its sand table wargaming. There are metal ground vehicles and helicopters in this scale, which is a near "one-quarter-inch-to-six-feet" scale. The continental powers of NATO have developed the similar scale of 1:300, even though metric standardizers really don't like any divisors other than factors of 10, 5, and 2, so maps are not commonly offered in Europe in scales with a "3" in the denominator.