Hazard troopers wore a very heavy suit of body armor that offered complete immunity to temperature extremes, immunity to acidic damage, as well as invulnerability to small-arms fire. Their air supply lasted for three days, and was enriched with beneficial bacteria. The armor was also a functioning space suit which could keep the wearer alive in a vacuum or underwater environment for up to three days. Hazard trooper armor was lightsaber resistant to a certain degree.
Hazard troopers had similarities to Dark troopers in that they were cyborgs, since they had their limbs removed and replaced with mechanical versions of them, though they were biological beings and not droids. Stormtroopers who were selected for hazard duty were required to undergo cyborg limb replacement to supply them with the necessary strength and stamina to operate their armor for extended missions. Hazard troopers were commonly equipped with either an Imperial heavy repeater or a Stouker concussion rifle, or, less commonly, a FC-1 flechette launcher.
They were relatively slow moving, but had very heavily armored suits to compensate.
- Star Wars: Jedi Knight: Jedi Academy (First appearance)