The EnVision T8 is available in 4' with a built in emergency system. You must bypass the ballast and wire both ends directly to line voltage. The aluminum backed bulb makes it OK for food areas, the CCT is consistent with our other tubes, to ensure end user satisfaction. Whenever power is suddenly lost, this unique led tube will automatically turn on, with the built in lithium battery, which can provide emergency light for 90 minutes. With normal lumen being displayed at 2000lm, the emergency lumen will be 380lm. The tube also features a test button to pass inspection.