I used Avent bottle warmer. Cons is that it takes time to warm up the water unless u pour hot/warm water in it. And the milk will be so hot if u leave it for too long. Aside from that, if you are always on the go, there’s a lollababy bottle warmer. I just ordered but yet to try, based on reviews seems good. But full charge can only warm up up to 6 times I think..