Similac Advance infant formula is an iron-fortified, milk-based formula that provides complete nutrition. It may be used on-the-go as a quick, meal supplement or regularly as a nursing alternative. Similac Advance infant formula is ready to use - no need to waste time measuring and mixing the formula. Plus, it comes in a conveniently shaped bottle, so you may hold both bottle and baby while feeding. Only Similac products have the EarlyShield nutrient blend.