The 24-Channel GS Hybrid DVR with Digital Deterrence & 4TB HDD from Speco Technologies has a user-friendly and intuitive GS interface optimized for full HD monitors. Its innovative side control bar interface enables immediate access to every function while minimizing distraction from the live view screen. Also, the well-arranged setup menu with 3D icons makes this unit both intuitive and stylish.The Digital Deterrent feature that is built into the DVR is triggered by motion-detection or alarm input activation that initiates visual indications, audio warning, and advisories. The visual part of the Digital Deterrent is a strobe or light that will be activated when motion or an alarm input is detected. Speco Technologies DVRs are equipped with a Form C contact that activates during these events. The audio output of the DVR is a line-level output and requires an amplifier (not included) to amplify the signal to be heard.