A large clump of sparklers that are air tightly wrapped with electrical tape. Once the fuse is lit, it takes about 50 seconds to detonate. Detonation occurs when all the sparklers in the air tight tape go off at the same time compressing against the tape and eventually going off. Once exploded a sparkler bomb of 16 standard sparklers has the equivallant of 1/4 a stick of dynamite.
I used a sparkler bomb to blow the door off a soda machine.