Those nipple suckers in black are shaped like the transparant SuppleNips but the material is a bit thicker and sturdier. I chose a medium size 3XL. I like to alternate between bigger (5XL) and smaller (4XL, 3XL) sizes.
With a smaller diameter you will stretch the nipple more. With a wider diameter your will make a thicker and cone shaped nipple and suck in the areola as well.
I think both is important. Making nipples thicker and longer. This is the an efficient method and will create satisfying permanent results.
