Hi Twoyearwait
We use 2 fingers. By putting one finger at one side of your cervix and the other finger at the other side of your cervix we are able to measure how far dilated you are.

IK
I never do routine internals they usually tell you nothing and it can be quite embarrassing for the woman to have to go through that. In fact most of the births I have attended I have not performed an internal at all. Most of the time a midwife can tell what is going on just by watching the woman and looking for the little signs that you all give.