Voltage range is the span of supply voltage within which a product is designed to operate. In Nordic Lights product data, the preferred label is Input Voltage DC. It must be distinguished from Nominal Voltage DC, which identifies the intended vehicle-system class. The available voltage at a lamp can vary because of battery state, alternator output, cable losses, and switching events. A product must remain within its stated operating range during normal use. Separate specifications may address transient overvoltage, reverse polarity, undervoltage behavior, and other electrical disturbances that are not defined by the range alone.