With my tunnel plug holding my cunt open, I penetrated my cervix with first a 7mm rosebud sound and then an 8mm sound. They both go past the os easily, but you'll see that I have to do some maneuvering to get the angle right to go any deeper! After that, I leave the tunnel plug in while I use a vibrator on my clit, so that you can see inside my pussy as I cum repeatedly.