The only bad thing about them is the housing is short. You have to either use it without a focus ring, or use something like nail polish to fix it to the first turn on the focus ring or knob. They come free with any module you buy from the Chinese, AixiZ, or DTR.
I have a 520nm AR coated two element glass lens scheduled to get here tomorrow. I'm hoping it does as I want to see if it will actually tame the rectangular artifact in all these Sharp diodes as well as the acrylic lenses do.