QNAP VS-4016-PRO-US 4-Bay NVR 16-Channel Surveillance System CPU: Dual-core Intel? Atom? processor DRAM: 1GB RAM Flash Memory: 512MB DOM HDD: 2.5/ 3.5" SATA x4 HDD Tray: 4 x Hot-swappable and lockable tray Form Factor: Tower USB: 5 x USB 2.0 port (Front: 1; Back: 4) eSATA: 2 x eSATA port (reserved)