Using 22mm and 19mm! But better to measure cos everyone is diff. Heck even left n right can be different. I go for Loveamme cos it’s the only one that can customise L and R!
I started off with 19mm but it became a little tight after a while so I upsized to 21mm! Used the 21mm for about a year before I stopped pumping.
You will have to measure and get your own flange. Everyone is different.