Klos is a rock planet with almost no atmosphere to speak of. Consequently, the planet retains fairly little heat considering how close it orbits to an energetic star. The relatively mild temperature made Klos attractive for robo-mining, with an emphasis on platinum. The planet also has an abundance of sodium oxide, used in the manufacture of lye, but profit margins on that compound are thin by comparison.
The Reapers have destroyed the orbital stations surrounding Klos and cut the strands of the space elevators that earlier generations of batarians used to transport goods to orbit.