Temperature-dependent resistor used to protect against overheating.
KTY sensors equipped with PTFE insulated lead outs, to prevent overheating.
NTC sensors equipped with PTFE insulated lead outs, to prevent overheating.
PTC sensors equipped with PTFE insulated lead out, to prevent overheating.
Bi-metal switch (Klixon) with insulated lead out, to prevent overheating.