I make these labrets by first melting steling silver in to a ball that I then flatten with a hammer, this gives each piece a very unique and organic feel, no piece is alike.
They measure around 3mm in diameter and because of the way I make them they're not perfect circels but rather roundish, see pictures for refrence.
The bioflex post comes in 18g (only 6mm and 7mm length) 16g or 14g and in a number of different lengths. The 3rd picture shows it with a 9mm 16g labret.