The T-289 Gas Grenade was a gas grenade produced by Czerka Arms. When detonated, each grenade released T-289 stun gas, which caused disorientation, nausea, and vomiting. The gas was nonlethal, except in very large doses, and ineffective against targets wearing protective breath masks.
The stun gas was useful against a wide range of alien species, although its effectiveness could vary depending on the target. While a Human would go down quickly from T-289, a Wookiee could still get in a few good swipes before finally passing out.