GEN-III OMNI-V–VII devices developed in the 2000s can differ from standard generation 3 in one or both of two important ways. First, an automatic gated power supply system regulates the photocathode voltage, allowing the NVD to instantaneously adapt to changing light conditions. The second is a removed or greatly thinned ion barrier, which decreases the number of electrons that are usually rejected by the standard GEN III MCP, hence resulting in less image noise and the ability to operate with a luminous sensitivity at 2850 K of only 700, compared to operating with a luminous sensitivity of at least 1800 for GEN III image intensifiers. The disadvantage to a thin or removed ion barrier is the overall decrease in tube life from a theoretical mean time to failure (MTTF) for Gen III type, to MTTF for GEN IV type. However, this is largely negated by the low number of image intensifier tubes that reach of operation before replacement.