BPA-Free and made of soft, durable, flavorless silicone, Specially design for newborns and preemies with a slower, more controlled flow rate, Wide, breast-shaped nipple promotes natural latch-on and makes it easier for baby to combine breastfeeding and bottle feeding, Innovative twin valve design reduces colic and discomfort, Recommended for Philips AVENT 2 oz and 4 oz Natural bottles