A friend has asked me about this - I don't know the answer so am turning to you guys to see if someone knows.
A display at a market using a laptop would be greatly enhanced by the use of a second screen attached to the laptop, that could face a different direction for the public to see. However, there is no power outlet available at the site, so the screen would have to be powered by the laptop.
I assume the laptop is a Windows-based one, but I don't know any details at this stage. I can ask if it's relevant.
Does such a screen exist?