The one thing commonly overlooked when selecting CCTV equipment is the hard drive (HDD) size within the Network Video Recorder (NVR). The size will depend on what cameras you have selected and for how long you wish to store the footage. A very rough rule of thumb is 1TB of storage per camera will normally result in 4 weeks of footage before that footage is over written. You can find formulars online that can calculate the exact TB required for the installation.