Nvr44-4Ks2/Nvr44-16P-4Ks2/Nvr44-4Ks2/L/Nvr44-16P-4Ks2/L/Nvr44-4Ks2/I/Nvr44- 16P-4Ks2/I/Nvr44-Ei/Nvr44-16P-Ei Series; Nvr48-4Ks2/Nvr48-16P-4Ks2/Nvr48-4Ks2/L/Nvr48-16P-4Ks2/L/Nvr48-4Ks2/I/Nvr48- 16P-4Ks2/I/Nvr48-Ei/Nvr48-16P-Ei Series - Dahua NVR21-4KS3 Series User Manual