A Kryptonian Signal Jammer was a piece of Kryptonian technology that was used to block the signals of enemies.
When General Zod and his Sword of Rao invaded Earth 33 years after Krypton's destruction, they were defeated and sent back to the Phantom Zone by Kal-El, the last Son of Krypton. Some of the Sword of Rao's equipment was left behind however, including a Signal Jammer.
Criminals used one of the left behind signal jammer's to break into Wayne Enterprises R&D Facility in Metropolis. As they were confronted by Superman while they made their escape, a captured Bruce Wayne knocked out his guard and used the signal jammer on a different frequency to subdue everybody, including Superman.
- Batman v Superman: Dawn of Justice: Field Trip (First appearance)