[marcosdumay]

It's clearly a typo, and should be 5V.

But then you get 5V 5A ... 27W that is clearly incorrect too. So my guess is nobody is proofreading the technical specifications, and everybody that cares was kept away from that page.

[nimmen]

5V * 5A = 25W, no PSU is 100% effective so 27W is reasonable requirement

[marcosdumay]

You don't specify a PSU by its energy consumption. You specify it by output.

Also, that 92% efficiency, is believable, but a bit high for a 5V 5A PSU (this is a difficult combination). I would expect any such unity to be marketed as high-efficiency.

[ralphm]

I expect it is 27W to support 9V 3V, not because of tolerances per se. (Source https://www.sparkfun.com/products/23583)