Size A: For light/medium menstruation and if you have not yet had a baby. Size B: For medium/heavy menstruation and if you have already had a child via vaginal birth. Size A : Diameter = 4,0cm - Stem length = 2,0cm - Cup length = 5,0cm - Total length= 6,6cm - Volume = 25ml Size B : Diameter = 4,5cm - Stem length = 2,0cm - Cup length = 5,2cm - Total length= 7 cm - Volume = 30ml