They both heat the bottom and sides. The first gen peak (non pro) was bottom heated only….I recall, it has side heating, which the Sai does not, but I figured the relatively small doses I will be using should work fine without it, and the side heating uses extra battery capacity. I suspect that both the Carta and the Peak control atomizer temperature the same way, but if the online information confirms that, I have not noticed. Also, I
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