The XT45A or F9031A is a thermal delay switch with a single set of change-over contacts rated at one Amp at 250 Volts.
The electrodes are held within a ceramic block.
The heater is within the vertical ceramic tube and heats the central bi-metallic strip electrode. The latter bends when hot to close the normally open contact.
The heater is a single strand.
The thin glass tube envelope is 18 mm in diameter, and excluding the base pins is 57 mm tall.
