Stun grenades, also known as flashbangs, are non-lethal weapons used by the Tau'ri.
Stun grenades take 1.5 seconds to detonate once the pin releases the spoon and it detaches from the grenade. They are filled with a mixture of aluminum and potassium perchlorate which, when ignited, produce a high-pressure wave with intense light and sound to temporarily overwhelm the intended target's sight and hearing for approximately ten seconds. The light is 2.4 million candle-power and the sound 175 decibels. (SGA: "Suspicion", "The Brotherhood")
The Atlantis expedition used flashbangs against the Wraith and the Genii. Within the first few weeks of operation, in 2004 they used them to ambush the Wraith in the hopes of capturing one, by stunning a Wraith warrior, and later tasering him. Unfortunately for them, the warrior managed to blow himself up before capture.
Later in 2005, Major John Sheppard's team used spare flashbangs against Acastus Kolya and his fellow Genii to prevent them from stealing the Potentia a Zero Point Module the expedition needed to power Atlantis. The grenades stunned the Genii long enough for Teyla and Ford to take out three soldiers and Sheppard to overpower Kolya.
Sheppard later used one against a Wraith warrior while on a mission to destroy a hive ship and ne is later used during a rescue mission to the Wraith weapons research facility to stun the guards so they can be quickly and easily taken out by the rescue team.
In 2009, Doctor Jennifer Keller carried a flashbang with her on a mission with Ronon Dex to PX5-442. When ambushed by an insane Wraith worshipper, Keller detonated the grenade, causing the worshipper to accidentally shoot herself. (SGA: "Suspicion", "The Brotherhood", "The Lost Boys", "Reunion", "The Lost")