How do you use these? I'm guessing that they connect to a syringe and then you connect a needle to the other end of the filter and inject it into a sterile vial?
It depends on what kind you have. There are those that connect between the syringe and needle. Then there is another kind where it looks just like a needle where you draw back into the syringe it filters out glass and debris that is too big to pass. you remove the filter and put on a regular needle and stick it.