The Remote Hacking Device is a gadget used in Batman: Arkham Knight. It replaced the Cryptographic Sequencer in the said game, but works the same as the Sequencer in every way.
The Remote Hacking Device appeared in this prequel storyline as a part of Batgirl's Utility Belt and was one of her primary gadgets. While it functioned similarly to how its future counterpart handled, it also appeared to be far more advanced then Batman's version as it was capable of running machines that Batman's couldn't such as cranes, and was able to use certain objects in more than one way. While it was never stated, it was implied that Batgirl herself was the inventor of the device for her own use in the field. Another possible explanation is that Batgirl's hacking skills are simply superior to Batman's, allowing her to use the device in more ways than he could.
Batman obtained the Remote Hacking Device from Lucius Fox at Wayne International Plaza after he destroyed the Watchtower that protected the Stagg Enterprises Blimp and contacted Lucius that he would need it in order to get to the blimp. The Remote Hacking Device did what the Cryptographic Sequencer did, but it could also hack and control enemy drones, turn consoles on and off, could tilt Stagg's Airship, and certain things could be hacked to takedown/stun enemy's such as locking doors, spraying paint explosions. It couldn't be used as a radio anymore, and it had a longer range.