If you have a summer baby you might find the standard Heart2Heart insert a bit hot when the temperatures get above 25 degrees. In the heat of NZ summer (if it ever arrives!) we recommend that you dress your baby in just a singlet and nappy when they are in the insert, or a summer shortie onsie is fine too.
But there is another option now too. ERGObaby, always the innovators, have just released a new Heart2Heart Performance Insert with CoolMax, the wick away fabric designed to draw moisture away and keep baby comfy and cool at the same time.