I bought the Kentfaith M150C for my 7 year old for his birthday and he really liked it. I also bought the Kentfaith 25 Prepared Biology Microscope Slides and the Gosky Microscope Lens Adapter.
Back to the Kentfaith M150C, it‘s solidly built and I did not notice anything wrong with it until I put the 3 AA batteries in the bottom. It took a while, but I noticed that it's missing a spring in one of the battery slots, thus not making battery connection. I was utterly disappointed and thought I had to do a makeshift fix to get this to work. I decided to look at the power adapter and noticed that it supported 110v - 220v, to my surprise, because on their website it mentioned that it only supports 110v (I live in a 220v country). So, we were able to enjoy the microscope on his birthday.

This was definitely a Quality Control issue and I think Kentfaith should revisit their factories to ensure they deliver quality products for their customers. Be it their cheapest to their most expensive models, small details like this can definitely hurt the reputation of the company. I chose Kentfaith because of the favorable reviews and I chose this particular model for it's metal construction, I wanted something to last. But the missing spring in the battery slot is a disappointment.