A resistance box is a typically compact piece of equipment that contains multiple resistors hooked up to one or multiple switches and is designed to provide multiple electrical resistances. The primary benefit of having a compact way to alter electrical resistance is that it removes the need to actually change resistors or unit design just to change resistance. Many resistors can be set at many levels, providing immediate access to a combination of resistances, a possibility useful for many applications requiring electrical manipulation. The complexity of the resistance box will probably change based on the application, though many of these units are set to standard values.
A resistance box is a rheostat, a device meant to maintain specific electrical currents. This can be useful for testing the physical properties of electricity and for various other electrical applications. Early rheostats held only one current, though they evolved into more complex versions that can provide nearly unlimited variations in resistance at any given time. A modern resistance box can have a large range of resistances to make it useful in many situations. Useful perhaps in a laboratory or for experimental purposes, these devices usually contain some combination of resistors, mechanical switches and precision instruments.