The Regin smoke cartridges are an economical and practical method of generating a realistic swirling, non-toxic smoke with a particle size of .3-2.5 microns. The smoke contains no zinc or oil and leaves behind no residue. This premium product is the best tool for testing, duct systems, providing a visual display of airflow for balancing or leak detection, exhaust air systems, smoke stacks, chimneys, fume hoods, negative air pressure testing, smoke alarms, fire drills, film and photography, verification of high efficiency air filter operation, and virtually hundreds of other applications. With an increasing emphasis on environmental and safety issues, this is an invaluable, practical and economic tool. Regin Smoke Cartridges are extremely stable and have a long shelf life up to 3 years.