The perfect prep machine is not compatible with SMA stay down milk as this milk needs to be made up with fridge cold cooled boiled water. As I understand other "staydown" milks such as Aptamil anti reflux and Cow & Gate anti reflux also require being made up at a cooler temperature (hand hot water, more like 40-50 degrees not 70) so cannot be used with the perfect prep. The perfect prep makes up feeds with a hot shot of 70 degrees plus water and then tops that up with cooler water to produce a feed that is body temperature aka the "perfect" temperature. It can be used with all "regular" powder formula (first milk, hungry baby, follow on etc) and comfort milks (sma comfort, Aptamil comfort, C&G comfort etc). I am unsure if it is compatible with other medical formulas such as Nutramigen (sp) and Neocate etc. Xxx