Kiinde Kozii warmer can fit Comotomo bottle.
You can get it from Amazon.
http://www.amazon.com/Kiinde-KK-R1-NA-Kozii-Bottle-Warmer/dp/B005G3QSF2
Alternatively, you can warm the breastmilk in a smaller bottle using your existing Avent or Dr Brown warmer before transferring the milk into Comotomo bottle.
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