5-20 cm. According to relevant public information, the skirting shelf changes with the size of the skirting. Ercock, or double-ring firecrackers, is a traditional folk product, which is often used in festivals, weddings, commemorative ceremonies and many other occasions. It uses the expansion of gunpowder explosion to explode paper and make noise to entertain the masses. Because of its two sounds, it is called Erkicker.