Some electric lanterns use miniature fluorescent lamps for higher efficacy than incandescent bulbs. Originally Maglite flashlights used krypton or xenon incandescent bulbs. Fluorescent lamps convert more of the input power to visible light than incandescent lamps. Electric currents cause Joule heating, which creates light in incandescent light bulbs. Fluorescent light fixtures cannot be connected to dimmer switches intended for incandescent lamps. Fluorescent lighting is more energy-efficient than incandescent lighting elements. A brighter light results with more blue color than conventional incandescent lamps. However, low frequency also causes noticeable flicker in arc lamps and incandescent light bulbs. Traditionally, incandescent and halogen bulbs were used. They contained relays or stepping switches controlling digits consisting of incandescent light bulbs. Fixture manufacturing began soon after production of the incandescent light bulb. Consumption of incandescent light bulbs grew rapidly in the US. The 2007 Energy Act mandates energy efficiency and labeling standards for incandescent and fluorescent bulbs. LEDs are highly efficient at producing colored light compared with incandescent lamps and filters. They have much higher efficiency than incandescent lamps.