TEREA sticks contain a metal heating element coated with stainless steel, that heats the tobacco from within. HEETS sticks do not contain this heating element inside the stick, as the heating element sits inside the IQOS device. TEREA sticks can only be used together with the IQOS ILUMA devices series and cannot be used with the previous generations of IQOS devices (IQOS ORIGINALS, IQOS 3, IQOS 3 Duo, IQOS 2.4, IQOS 2.4+ and IQOS Multi.