Compound Adjectives in English

When you write a number noun compound adjective, you need to join the two parts together with a hyphen. There's no s because the word kilo r functions as an adjective here and we can't make adjectives plural. So high plus quality equals high quality, like high quality vehicle. Low plus cost equals low cost, like low cost air line. Some more examples with length are a 26 mile race, a six foot man.