Brightsparks 4 Kids-Variable-Resistor-Module-Brightsparks 4 Kids-ST007-p-The-Variable-Resistor-unit-can-be-used-with-the-Brightsparks 4 Kids-Beginners-Electricity-Kit-either-as-a-speed-control-for-the-motor-module-dimmer-switch-for-the-bulbs-or-volume-control-for-buzzer-module-A-variable-resistor-varies-electric-current-&-is-commonly-used-in-a-household-lighting-dimmer-switch-but-has-a-number-of-other-applications-p-Brightsparks 4 Kids-Variable-Resistor-Module