These Regin Fumax KS Smoke Pellets are designed for testing flues or chimneys for leakages. They produce a dense smoke to highlight potential issues and are compliant with Bs5440 part 1. Each pellet offers approximately 60 seconds of burn time, producing an estimated 15 cubic meters of smoke with ideal density for flue testing. The pellets are encapsulated for ease of use and disposal. Sold in various colours and available as matches or cartridges.