Multi-perforated, for better milk delivery.
With transport box that allows sterilization in the microwave, to eliminate 99.9% of bacteria and fungi that cause oral infections such as oral candidiasis.

How to know what size to choose? To measure nipple size, use a ruler or measuring tape and measure the distance, in centimeters, from the base of the nipple. Be careful not to include the halo. Add 4mm to your measurement and this is your final nipple size. Size 1 is up to 24mm and size 2 from 25mm.