Chinese lenses are still russian roulette
Tried new line of Chinese metallographic fluorite microscope lenses (LU Plan Fluor). M26 threading, 60mm parfocal distance could cause mounting issues on many generic microscopes. I was saved by 0-height adapters to M30 threading of my microscope.
The price is getting higher, 5x and 10X are 120-175$ each, and 50x is 460$. Unfortunately, they all disappointed me. Image quality with them dropped significantly to the corners and there were significant chromatic aberrations. They could still be better than "200$ for a set" microscope lenses, but not matching good Olympus ones. All lenses were returned to manufacturer.