color timer

A light bulb-like instrument usually attached on an Ultraman's chest. Emitting a steady, blue light at full power, it blinks red if an Ultraman is running out of power or if he is approaching to his time limit. If the Color Timer stops emitting light, it signals either the death of an Ultraman or he'll simply reverts back to his human form. It is also known as the "Warning Light" in the English dub.

Its name differs, depending on which universe, for example; in Gaia's world, it's known as the Life Gauge, or in Nexus' world, it's the Energy Core. And the U40 Ultras instead obtain a similar item known as the Star Symbols.