Most 12v DC power supplies are 5.5mm x 2.1mm, this one fits 5.5 mm x 2.1mm and 5.5mm x 2.5mm, is UL Listed, has great reviews and is reasonably priced. It also meets or exceeds your other specs. On amazon ==>> here.
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That one also would work well. It has the size connector that is most common for 12VDC cams, NVR's, routers, modems, etc. which is 5.5 mm x 2.1 mm (inside barrel). That is most likely what your NVR is but if you can confirm that then go for it.
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Physically larger and has higher current capacity but if you prefer the small, separate AC cord plugged into outlet vs. a 'wall wart' that can take up space, then it should do the job as well. It's also UL listed.
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