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 air-flow, for balancing or leak detection in; exhaust air systems, smoke stacks, chimneys, fume hoods.