There are several requirements of hard disk drive (HDD)
1. The disk should better be the one used for survilliance, not for computer system.
Here is reason.
2. The type should be SATA. SATA2(3GB/s) or SATA3（6GB/s）is recommened. If you connect a USB stick or drive to USB port of DVR, DVR can only back up video from internal hard disk drive to USB stick, but can't record to it directly.
3. We recommend 5400 RPM.
4. size is 3.5” .
5. The brand could be Dest digital or Seagate.
6. The capacity should be less than or equal to recorder's maximum capacity.
Here are some models we recommend. But please notice it is just for your reference.
The form below is the maximum capacity for DVR on different models.
Here is the method to check model number. /kb/content/1/100/no20-where-to-check-model-number-of-device.html
Note: Before installing the hard drive disk, please power off the system if it is on.
Step 1 Loose the five screws which are fixing the box cover.
Step 2 Push forward the cover to the end and remove it.
Step 3 Connect the hard drive to the DVR System
Step 4 Turn on the dvr and check whether it detects the hard drive.MAIN MENU---—INFO—----HDD INFO
Then, power off the system.
Step 5 Fix the hard drive inside the box.
Put screws on to fix the hard drive inside the box.
Step 6 Put the cover back to position and install the screws to fix it.