Studio Technologies IFB Plus Model 2A Central Controller: This single rack-space unit contains all the circuitry to implement a sophisticated 2-channel IFB system for electronic news gathering (ENG) and outside broadcast (OB) vans, satellite news gathering (SNG) vehicles, and mobile production facilities. Interruptible foldback (also known as talent cueing) allows reporters and other on-air talent to receive program audio along with audio cues from production personnel, generally directors and producers.