You may make your formula with warm water anywhere. No matter water or milk, it can be warmed in Bololo portable milk warmer easily. It can be held with travel bag or stroller. With the super charging power adapter, the Bololo portable milk warmer could be charged in 2 hours to 100% or 80% in 1 hour. And it can heat up 9 ounces milk/water up to 7 times after fully charged, so it could support your whole day outside travelling.