That model is an Acusense which has a basic AI on it to detect human and vehicles to lessen false alarms. Since it is the "77" series then it will have four SATA ports instead of two SATA with the "76" series. The AI can be used with four regular cameras. If you want AI on cameras after the fourth then you would need to get a camera that has AI built in. All in all it is a decent unit. The only downside I can see is that there has not been any firmware updates for this unit. Model without the AI has firmware up to 4.40.010 where as these models with AI (Acusense) is only at 4.1.15. Hopefully it is because there are no issues with it but I know any model starting with GUI 4.0 has the file system/video bug that didn't get fixed until firmware 4.22.005.