Fun Cup Size A - Smaller (Length 5.32 cm / 2.1 in. Diameter 3.95 cm / 1.56 in. Volume 20 ml / 0.68 oz). Firmer silicone for greater control while placing and adjusting a smaller cup. Good for: lighter flow, people who have never given vaginal birth, someone with a shorter vaginal canal. Fun Cup Size B - Larger (Length 5.82 cm / 2.29 in. Diameter 4.32 cm / 1.7 in. Volume 30 ml / 1.01 oz). Softer silicone for a comfortable fit that holds a heavy flow without feeling intrusive. Good for: heavy flow, people who have given vaginal birth, people over 30.