The Philips AVENT variable flow nipple is made of soft silicone and provides an extra fast flow and accommodates thicker liquids. Flow rate can be varied by turning the bottle to align the I, II, or III markings on the nipple with the baby"s nose. The naturally shaped nipple makes it easier to transition from breast and bottle feeding and the anti colic valve promotes active feeding and reduces fussiness and colic with less air in baby"s tummy. Classic and Classic+ nipples are the same.