PetAg Nurser Bottle is a specially designed bottle by professional vets to offer your pets a natural-feeding action. It's made from durable plastic that's guaranteed to last even with repeated use and sterilization. It's also marked with graduations to help you easily monitor your pet's food intake so you can prevent over and underfeeding. It comes with a durable and flexible latex nipples without holes to let you customize the formula's control flow. The 2 oz. bottle is best used by small animals and the 4 oz. bottle for larger animals.