Our photostability chambers have four shelves with 10 lamps per shelf – 6 cool white fluorescents (400-700 nm) and 4 black lights (300-400 nm). These ten lamps create a bull’s eye pattern on the shelf below, resulting in a circle about 16″ in diameter for product placement. Light intensity within the circle will be an average intensity of 16,000 lux VIS and 10 watts/m2 Near UV, plus or minus 10%. The typical photostability test lasts 3 days for Optional II testing. Customers that need only a small amount of shelf space for testing can buy one, two or three shelves…instead of paying for all four.