6" mortar blasting out of a steel pipe. Great big boom and wonderful colors. Unfortunately, $22 each limits the number of those we get. The rest are 3" and 4", some 5" as well. The 4th is an expensive holiday for us, usually we spend between 600-700 dollars. It's worth it, we're on a private lake in Upstate NY and we put on a great show for all the neighbors. We've been doing it for 15 straight years, so we have plenty of practice and expertise. But, they're nothing to fool around with, serious business.