Love your Janice tat. Could have started with a 7 or 8 mm sound and gone up from there. 7-8 is the average size of a male urethra so you can basically take everything 6mm and under and bend it into modern art or something, anything but use it. False passage and all that. And Especially if you are exploring deep play. My two cents worth. I sound 13.5mm x 11.5 inches to get to the prostate and more. The feeling is unique. Really. Just be careful.