In the item description, the microscope is advertised with 200x or 20x magnification. I then once photographed the millimeter scale of a ruler in the "200x" mode. To my surprise, two millimeter strokes easily fit horizontally in's field. More specifically, the horizontal field of view is 1.5 mm wide. According to the data, a 1/4 "CMOS chip (0.63 mm) is used. Thus, the actual optical magnification 1.5 / 0.63 = about 2.5x.
This surprised me especially because another reviewer has stated in its assessment, the increase was "visually".
Of course it can be argued that because of the relatively high pixel count and the large representation obtained on the computer screen a greater magnification. However, this depends on the screen size of the user and is ultimately only a scaling of the image similar to a digital zoom. However, the actual quality of the display depends mainly on the resolution. The resolution per pixel is in the very best case 1.5mm / 1280 pixels = 1,2μm. In my experience, is reached about half of this value on the basis of digital camera artifacts and the quality of the optics.
The poor rating I give also because the manufacturer avoids sent clear indication of the quality of the optics. So Does the technical data sheet neither the working distance (measured from me 20mm) nor the actual optical magnification. Thus, the marketing of the company. Bresser is not transparent and dishonest. In advertising, which is indeed normal but still very annoying for customers.
If you approach with realistic expectations of this product you can certainly have fun with it. Unfortunately, advertising and other reviews with incomplete or incorrect information arouse false hopes and lead to disappointment.