Dr. Brown's Ultra-Preemie level nipple is the slowest flowing nipple compared to any other brand on the market and 35% slower than the Dr. Browns Preemie level nipple. Since it was created through a cohesive effort between medical professionals and Dr. Brown's engineers, the Ultra Preemie nipple continues to be used as one of the most valuable intervention tools by top Feeding and Swallowing Specialists. The Ultra Preemie level nipple offers the most consistent and precise bolus flow rate that has been shown to assist in managing the typical to complex oral feeding challenges observed infants at preterm, late preterm and term age. The reduced flow rate allows infants the ability to safely and successfully orally feed by supporting their suck -swallow-breathe pattern with a reduced fluid bolus size and rate. Infants have been reported by medical teams in NICU's and hospital nurseries to transition to full oral feedings in less time than if an infant was fed with a faster flowing nipple. The reduction of bolus size and delivery rate provides the support to the infant in establishing the bolus control for a safe and positive oral feeding experience. They are safe for dishwasher and microwave steam sterilization. 100% Silicone; BPA-Free and Latex-Free.