I'm guessing feet since a 5 meter tall tent would be odd. My Mars II 700's have a 2 x 2 footprint in flower and draw about 350 watts. You can get as close as ten inches with some strains at sometimes and 16 is safe for all I've grown, photos only. They give solid buds 16 inches down when held 16 inches above the plant.
They don't have the best rep and it's not underserved, but they are still worth a look.