The ideal lip proportion is the ratio of 1:1.6 between the upper and lower lips. If you want your lower lip to be larger, use the Blocker to block suction to the top half part of the lip pump. If you like your upper lip to be fuller, blocker suction to the lower chamber. If you have very thin upper lip, use model B or D. These model can enhance the upper lip much better because you can use the pumps in revert position. When in doubt, buy a set as you will need both pumps (apple set or licorice set).