Firecrackers with two kicks are a traditional folk product, which is often used in festivals, weddings, commemorative ceremonies and many other occasions. They are carried away by the reaction force generated by the bottom powder hitting the ground. The principle is that the paper tube with double kicking firecrackers is divided into two layers, and the function of the lower gunpowder is to send firecrackers to the sky. The upper gunpowder will explode in the air 10-20 meters later.

Erguotou is a kind of firecrackers, and its powder is divided into two layers by cement or soil. The "back door" at the bottom was not blocked tightly, and the airflow generated by the lower gunpowder explosion "pinged" through the back door and sprayed downward. The downward jet of air generates upward thrust, pushing firecrackers into the air. At this time, the fuse just ignited the gunpowder sealed at the upper end, and the second combustion exploded rapidly, and the two kicks blossomed with a bang in mid-air. Fireworks also rely on the rapid combustion of gunpowder-the thrust generated by the explosion.