Willen I will answer Your question again - the mics are having no FET inside and are not polarised.
I tested them using schoeps original body - preamp.
Sound is quite ok, but not overhelming.
It is comparable to most chinese low - mid cost mics.
What made me try these is the fact that chinese do
sell some good stuff for no money, after they produced long enough parts for more expencive products.
I will use them for special multichannel recording, and they are perfect for my purpose.
If You are able to build circuit to polarise and properly power
true condenser Mics, than it is a more than good Mic Capsule for the price.
I know that maybe there are Electrets arround looking similar,
but this one which is currently offered all over the place on ebay,
ali, banggood etc is as I am telling You : true condenser.
If You want similar - and easier solution,
take JLI TSB 2555 - it is polarised, and that will make circuit much simpler.
2 FETs and few resistors, capacitors and off You go