Kig-Yar Rangers are trained as zero-gravity combat units. The Rangers wear vacuum suits, and they are used to assist the Sangheili Rangers. They do not wear jetpacks, and instead are equipped with surface-adhering boots, possibly magnetic, which allows them to walk safely in zero-gravity environments.
The first known contact between Kig-Yar Rangers and humans occurred on board This End Up, a freighter attacked by Minor Transgression in 2525. Following this encounter, they were deployed in combat from as early as 2531 until at least the Fall of Reach in late summer 2552.
Kig-Yar Rangers were first mentioned in the Halo: The Fall of Reach during the Spartans' mission to recover the UNSC Circumference's navigation database. They are described as clad in blue space suits, carrying Kig-Yar point defense gauntlets and plasma pistols like their regular infantry counterparts. They are shown in the Halo Wars: Genesis graphic novel inside the UNSC Prophecy, where they seem to wear a different suit with orange chest armor plate and purple clawed boots. They have no obvious helmets, instead being replaced by some type of energy bubble which produces oxygen for the Kig-Yar to breathe. Also, they wield a different kind of weapon that is strapped to the wrists of the Kig-Yar and also have no shields. In Halo 4, their appearance is drastically different, with their gear now looking like a Kig-Yar version of the Elite Ranger's combat harness from Halo: Reach. It is interesting to note that the helmets of Unggoy Rangers and Sangheili Rangers are clear leaving their faces visible unlike the helmet of a Kig-Yar Ranger, which is tinted.