Wide, naturally shaped nipple eases baby's transition between breast and bottle. Contoured nipple with gentle slope promotes proper latch-on and strong mouth seal just like breastfeeding. Soft, flexible silicone adjusts to baby's pressure for the right amount of liquid. Pediatric angled bottle helps keep nipple full which means less air in baby's stomach. *** All Stanford products are unable to be shipped via 2nd Day and Overnight Shipping methods. ***