- "This is a Goa'uld Zat'nik'tel. A weapon using a different form of energy, less powerful than that of a staff weapon. Less destructive, but still quite deadly."
The Zat'nik'tel, nicknamed Zat or Zat gun by Colonel Jack O'Neill, is a handheld weapon used by the Goa'uld and their Jaffa. It is in the shape of a serpent and was first encountered by SG-1 on Apophis's Ha'tak. Its energy output, in the form of blue electrical energy, is less powerful than that of a Staff weapon. It's an extremely efficient weapon and is used extensively by the Goa'uld, Tok'ra, Jaffa and Tau'ri.
The Zat'nik'tel 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 stun weapon. (SG1: "Seth", "Flesh and Blood", "Moebius, Part 1", "Moebius, Part 2")
The overall shape and size of the Zat'nik'tel made it something of an instant favorite after its discovery by the Tau'ri. Many member of Stargate Command use them in place of pistols and handguns when dealing with potentially dangerous targets on Earth itself. At a distance, it is difficult to tell that the Zat'nik'tel isn't a sidearm, and its stunning capability makes it easier to apprehend a target without injuring them.
- "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."
Zat'nik'tels are fired by squeezing the bottom curve where the gun is held. The Zat 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 will be necessary to kill (as evidenced by Colonel Jack O'Neill's being shot a variety of times throughout SG-1's various exploits). A third shot will disintegrate the victim and their clothing, and will also disintegrate small inanimate objects with low densities, leaving no visible trace of their existence (SG1: "Within the Serpent's Grasp", "1969", "Point of View")
The Zat has been shown to conduct through objects, stunning victims indirectly. The weapon has also been used as a tool to boost hyperdrive speed when 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 blast. It is capable of disabling Aschen defense drones with one shot. (SG1: "2010", "Lost City, Part 2", "Memento Mori")
It also appears that repeated attacks by this weapon causes most people to not suffer its effects with as much severity, as seen in cases where certain people are able to withstand the effects and remain conscious after a single shot. The second shot, on the other hand, is invariably fatal (on non-immune species) with only a single exception shown: When Major Samantha Carter's consciousness was replaced by an alien Entity, two shots left her body only brain-dead, allowing her consciousness to be transferred back into it. (SG1: "Prodigy", "Entity", "Lockdown")Zat blasts can be caught and rendered harmless by a Kara kesh as shown by Cronus when he was fired upon by Teal'c. (SG1: "Double Jeopardy")
- 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 ("Within the Serpent's Grasp", "Family", "Secrets" and "1969") in SG-1, all to disintegrate the bodies of Jaffa guards and material (to be removed from the timeline), and is mentioned one other time. Other "third shots" have been attempted, all on replicators, to no effect.
- Because it was not seen after the 3rd season, it's possible the third shot function was only present on older model Zat guns and that newer model ones only possessed two shot functions. The concept was not officially retconned, rather it was simply abandoned.
- However, given that when a "third shot" is used and there is no difference in the firing or the visual effect, it is likely the disintegration is caused by a build-up of the energy, not by any adden function or mechanism.