Zat'nik'tel

"This is a Goa'uld Zat'N'ktel. A weapon using a different form of energy, less powerful then that of a staff weapon. Less destructive, but still quite deadly."

- Teal'c

The Zat'nik'tel, nicknamed Zat or Zat gun by Colonel O'Neill, is a handheld weapon used by the Goa'uld. It is in the shape of a serpent and was first encountered by SG-1 on Apophis's ship. It uses a weaker form of energy compared to the staff weapon.

Overview
The Zat gun is a weapon of Goa'uld design. The safety is active when the zat is not in use and lays flat like a snake, but when it is turned on it stands up, alert like a snake. The weapon is unique in how it affects objects, animate and inanimate. Zats have been in production for at least five thousand years. The technology itself may be similar to an Ori wrist weapon.

Zat gun specifics
"The Goa'uld take great pleasure in discharging the weapon only once on a subject. Causing great pain, disabling them, but not killing them. The second shot will kill most subjects."

- Teal'c

Zats are fired by squeezing the bottom curve where the gun is held. The Zat gun is unique in the way it works. One shot is shown to incapacitate a victim and causes immense pain, while a second shot kills them. The shots do not have to be right after the other, as some have been killed several minutes after the first Zat blast ; however, an extended period of time between shots will cause the effect to wear off and two new shots are necessary to kill (as evidenced by O'Neill being shot a variety of times throughout SG-1's various exploits). A third shot will disintegrate the victim, and also small inanimate objects with low densities, leaving no trace of its existence.

The Zat gun has also shown to conduct to objects, stunning victims indirectly. The weapon has also been used as a tool to boost hyperdrive speed when Jack O'Neill used Ancient knowledge and required a short, powerful jolt to the modified engines, but is used as a tool to overload electronics in most cases as many conduits are not designed to handle that much energy in one go.

Zat guns have been shown to have little or no effect on Kull Warriors and Replicators, but they affect all other known species, including the Wraith. They are also far more effective than Wraith stunners as it never takes more than one shot to knock out a target with them.

Trivia

 * The producers and nearly the entire crew of Stargate SG-1 believe that the third shot of a Zat is a bit of a deus ex machina, and some think that the third shot effect is a bit silly/stupid, often not wanting to refer to it outside when it is used. Others even think that it completely makes no sense, as stated in many of the Stargate SG-1 commentaries. The episode Wormhole_X-Treme! even comments on the effect, with director of the show-within-a-show calling the disintegration idea "the stupidest thing..."
 * The "third shot" function of the Zat is only used four times in SG-1.