The short-term radon test kits used for screening purposes are inexpensive, in many cases free. In the United States, discounted test kits can be purchased online through The National Radon Program Services at Kansas State University or through state radon offices.[citation needed] Information about local radon zones and specific state contact information can be accessed through the Environmental Protection Agency (EPA) Map.[104] The kit includes a collector that the user hangs in the lowest livable floor of the dwelling for 2 to 7 days.[105] Charcoal canisters are another type of short-term radon test, and are designed to be used for 2 to 4 days.[105] The user then sends the collector to a laboratory for analysis. Both devices are passive, meaning that they do not need power to function.[105]