Master Series Pyramids Nipple Bulbs O Ring. Nipple Amplifier Enlargement Bulbs with O Rings. The Pyramid Nipple Amplifier Bulbs are an erotic way to have fuller, more erect nipples. This enlarger system has four graduated O rings to place over the nipples to keep them standing at attention! Simply slip the desired size ring over the open end of the pump prior to use, fit the glass pump over the nipple, and squeeze until you reach your perfect size. Then slide the stretchy rubber ring down over your engorged nipple, until it reaches the base. Two different sized pumps are included, for a custom fit on any size. Measurements: pumps are 2.63 inches long, Large Pump opening has 0.53 inch inner diameter, Small Pump opening has 0.35 inch inner diameter, O-Rings range from 0.33 to 0.54 inch inner diameter. Materials rubber, glass. Color: Black. Note includes two pumps and 8 rings.