The bulb is 9 watts and produces 800 lumens. The luminous flux from lamps is specified in lumens rather than candlepower. Some higher-power lamps (e.g. 600 watt) have efficacies of about 150 lumens per watt. A D2S HID burner produces 3200 lumens from approximately 42 watts during stable operation. Brightness (white light output) measures the total amount of light projected in lumens. The most efficient commercially available LED lamps have efficiencies of 200 lumens per watt (Lm/W). Light therapy uses a lightbox which emits far more lumens than a customary incandescent lamp. The efficacy of LEDs is on the order of 160 lumens per watt. Also, they have higher efficacies (lumens per watt) and better lives than non-halogen types. The efficacy (lumens per watt) is about half that of CFLs. Visible light output is typically measured in lumens. The relation between watts and lumens is not just a simple scaling factor. A miniature keychain lamp produces one or two lumens. Its peak light output was around a million lumens. Intensity is measured in lux, lumens and foot-candles.