Just a heads up: I have a couple similar digital microscopes that also have the controls mounted on the imaging device, and I can tell you they are a pain in the ass to operate.
Touching and twisting the focusing knob will move the device, and those movements - however small - have an effect that is literally magnified the more you are zoomed in. Then after you adjust to perfect focus, and release the knob, the device will ever so slightly move again, resulting in a not-in-focus image. This particular unit on Massdrop is going to be doubly troublesome because it not only has the controls mounted on the imaging device, but also the screen; everything is going to jostle.
In short: if you value a solid, well-focused image - especially at greater magnifications - then you need to purchase a digital microscope with the controls on a separate controller. I can't recommend a specific model though - prices, form factors, and features are all over the board.