how to find your size.

ngl this feels dumb as hell, i haven't stretched up in literal years and im not really one to ✨️accessorize✨️ ive worn the same single flare glass plugs but with my current job (i work with kids) just general rough housing pulls the o ring off the back and they flop across the floor. want to get some double flares but i cannot for the life of me remember what size im at.

Tl:DR I want new plugs but cant remember my size, how do i find out?