They're little paper strips (litmus paper I believe) and you can test the pH of basically anything with em lol I test my water randomly. Other liquids and foods sometimes
But I got them to check my bodys pH in my saliva and CM when TTC.
As far as being able to check for BV with them..BV is caused when your pH is outta wack. It gets too high. When I had BV in my 7th week my pH was 8.
It's a 6 now so I know its not BV. But possibly thrush, or maybe evn no infection. I've read today that some of your plug can come out, especially during a BM since you're using the sane muscles as when in labor, and it reforms itself. So since im not cramping or anything outta the ordinary i'm thinking that's probably what it was. I havent had it anymore since. I'm going to mention it Monday at my appt and will update everyone