The "Showstoppers" are a unique version of the Twin Revolvers that are used only by Jack Swift. These are Jack's primary weapon during all missions in which he appears and his only weapon in missions where he isn't controlled by the player. They are also his weapon in Showdown Mode. The player gets to use the Showstoppers when controlling Jack in the mission "Freak Show".
The Showstoppers can not be acquired by the player for use outside of the mission "Freak Show" or when playing as Jack Swift in Showdown Mode.