The LuxDrive™ 4006 DynaOhm™ Variable Resistor is an active device which functions as a dynamic resistor, changing its value to maintain a constant current flow.
Unlike a fixed resistor which will provide the proper current at a single voltage, the DynaOhm will maintain a fixed current over a wide voltage range.
This makes it very simple to power accent LED's such as the illuminated switches, just place this inline on the positive lead.