Another key parameter is regulation. Regulation is the ability of the DC-DC converter to maintain the output voltage within a specified range as input conditions change. There are two primary categories of DC-DC converters: regulated and non-regulated devices. Regulated DC-DC converters are used in applications where the input voltage is not well regulated. Fluctuations on the inputs will therefore not affect output voltages and driving subsequent downstream components. Non-regulated devices are used when the upstream signals are well regulated and line changes are minimal. The output voltages will fluctuate with changes in the line or the load. In general, non-regulated devices are generally smaller and less expensive than regulated DC-DC converters.