I copied this from the iolite site
The iolite Vaporizer is powered by butane gas, it fills with a minimal amount and holds a charge which allows for continuous vaporization for up to 2 hours.
The iolite Vaporizer contains a patented flameless gas catalytic heater & thermostat.
iolite Vaporizer Temperature Controller
With a thermostatically controlled bi-metal regulator, the iolite Vaporizer is able to maintain 374° F / 190° C + - 5°. The iolite Vaporizer utilizes a similar temperature regulator as the Volcano Vaporizer Classic.
iolite Vaporizer Healthy and Completely Inert
The catalytic conversion happens in an isolated chamber within the iolite Vaporizer so that butane can heat the unit but as it’s used it expels the butane as harmless water vapor through the escape ports located on the port of the unit.
Since the catalytic conversion on the iolite Vaporizer renders the butane completely inert as well as completely separating the reaction, there are no risks to your health.