Breaks

In a multi-break firework, stars are contained in separate cardboard compartments within the shell. Each container has its own bursting charge which lights and throws out the stars. In order to spread these decorations over a wide area of the sky, the container must burst open with tremendous force. The more the container can resist the explosion and bottle up its force, the bigger the display will be. Resistance comes from the container's heavy wrapping, which is designed to momentarily trap the gas and heat from the bursting charge.