Latex nipples are softer and more flexible, but they don't last as long. Silicone nipples are firmer and hold their shape longer. Orthodontic nipples, designed to accommodate your child's palate and gums, have a bulb that's flat on one side. This flat side rests on your child's tongue. Flat-topped nipples emulate the shape of a mother's breast.
Nipples are also available in a range of sizes and flow speeds.
You may have to try a few sizes to find one that works best for your child, but don't give an infant a nipple meant for a toddler. Once you've determined your child's preference, you can order enough to last for months. Check nipples periodically for signs of wear, such as discoloration or thinning, and replace worn ones, which could break and become a choking hazard. If you're weaning and switching to bottles, be sure to buy the right nipple for your child's age. Once you know your child's favorite, buy that style in bulk.