Mixie is the first baby formula bottle that can be fixed now and mixed later. The one of a kind baby formula can be filled in advanced and mixed at feeding time. Available in 4 and 8 oz. sizes. esigned by a dad who wanted a bottle that could be fixed now and mixed later, this ingenious little design can soothe a baby's hungry stirrings in two shakes! An internal chamber holds up to four scoops of formula and keeps it perfectly dry with an air-tight seal. Fill the 8 oz. bottle with water and pop it in your baby bag or purse, or stock your cupboards before leaving little ones with grandparents or babysitters. At the first sign of fussiness, the bottle's bottom button can be pushed in order to release the formula into the water.