Yeah, was thinking at least 7 inches, maybe 5 minimum, but the resolution would have to be good too. Not much point in a 7 inch screen that's a mere 640x480.

By the way, do you have specs on the power supply? I know it's 12 volts with a positive center pin and at least 1 amp, but the side/type of barrel connector I can't find. Also, any suggestions on lighting? I noticed that on Amazon, that one you posted is frequently bought with this lens:

https://www.amazon.com/Monocular-C-Mount-Industry-Microscope-Objective/dp/B016NUGHK2/

And this light: https://www.amazon.com/HAYEAR-Illuminator-Lighting-Industry-Microscope/dp/B08CBZZZD8/

Any idea if that lens is any good compared to that one on the eBay link? Or if that light would be any good since it doesn't seem to be adjustable like that other $100 microscrope I was looking at which had the lights on two flexible hands.