Innovative device for testing the tightness of various systems. Using generated smoke, which is introduced, for example, into the intake system of a car engine, it can detect even micro leaks that may cause, for instance, engine power loss. Designed for use wherever there is a need to check the tightness of closed systems, such as fuel lines, intake systems, tanks, etc., thus finding wide application in the automotive and industrial sectors. A simple-to-use tool filled with regular oil will facilitate and speed up the work of detecting leaks.