The arctic hayes smoke sticks kit is the first product on the market offering a pencil thin smoke pattern the smoke is non corrosive and not harmful ideal for testing for the slightest air movement gas spillage also for mandatory co spillage checks of boilercase sills after fittingre fitting and hvac air movementleakage checks the smoke sticks kit comes with 3 smoke sticks providing up to 3 hours of controllable smoke refill pack also available