Tricare and MaterniT21 test?

Hey ladies, I know that tricare doesn’t cover the MaterniT21 test unless your high risk (which I am not) so I won’t be covered. I was told I could do a survey at the end and only pay $300 instead of the out of pocket $1,100. However, it says it’s $300 “per test”. Is there more than one test that is ran? Or is it one test for multiple screenings? I don’t want to commit to this then end up getting charged more than $300 thinking it was all just one test. Does anyone have experience with this?