A lot of guys shoot ice, but I don't freeze things. I eliminate movement altogether. I stop atoms cold. I am the man who mastered absolute zero. 
Captain Cold built a gun, based on a cyclotron, which emitted blasts of ice and cold.
History
It has the ability to cause the molecules of its target to reach absolute zero, causing molecules to stop moving. The body can be re-animated with no damage to the subject by reactivating the molecules. This is different from Mr. Freeze's gun, which Cold considers sloppy, which somehow changes the chemical makeup of the victim to become ice.[1][2]
The gun can also slow down areas of air, which Cold uses to put nets around to slow the Flash down when he attempts to run through.[1]
Earth-One
In Earth-One continuity, the cold gun was created from equipment affected by a lab accident.
New Earth
In New Earth continuity, the cold gun was constructed by Snart based on schematics he acquired.
An early example of one of Cold's guns was kept at the Flash Museum. Wally West dismantled it an effort to learn how to modify a cyclotron being built at S.T.A.R. Labs so that would release a pulse of absolute zero temperatures across the city, halting an alien attack.[3]
Arrowverse
In the Arrowverse, the cold gun was built by Cisco Ramon to guard against the possibility that Barry Allen would be a criminal. Also, rather than build the gun, Leonard Snart bought after it was stolen by a S.T.A.R. Labs janitor along with Mick Rory's later flamethrower. After Snart and Rory were defeated and arrested, Cicso destroyed the guns. However, the two villains escaped and blackmailed him (by threatening his brother) into building new ones. While Snart did not build the gun and could not replace it himself, he boasts that he took it apart and reassembled it until he had the blueprints memorized, to the point he could recognize when Cisco attempted to sabotage it.
See Also
- Appearances of Captain Cold's Cold Gun
- Item Gallery: Captain Cold's Cold Gun
- Images featuring Captain Cold's Cold Gun