The IEC Rotary Rheostat / Potentiometer is for low resistance and high power. It is useful in the classroom where larger currents are required. Resistance is 5 ohms and power dissipation is 100 watts. This calculates to a permissible current of about 4.5 amps. The unit is fitted with 3x 4mm spin free IEC terminals so it can be used as either a rheostat (variable resistor) or a potentiometer.
The rar of the unit is open to allow students to see the construction of a Potentiometer or a Rheostat, however when used at currents approaching 5 amps, it will be dissipating up to 100 watts and it will be very hot. Always supervise its use.