This battery-operated lamp is so light and compact you can take it almost anywhere, making it suitable for those times when you need a UV source but don?t have an AC wall outlet available. They are the most powerful units of their type, and incorporate a specular aluminum reflector maximizes UV irradiance for even brighter fluorescent response. This lamp was also designed to provide hours of uninterrupted use. In fact, the BEA-140 can be operated for approximately five hours on fresh batteries. The BEA-160 features a transparent, plastic tube guard to insure against accidental breakage, and is constructed around a heavy-gauge, anodized-aluminum housing. Unit has a single 4 watt tube and uses ordinary "C" batteries. Peak Intensity at 6": 730 microW/cm2 with alkaline batteries. Dimensions: 3" x 3" x 7" Operating time: About 5 hours.