If you’ve been using fireworks since the days of British Standards you will remember that mines always contained their effects in one single internal cylinder (essentially a shell without a lift charge).
However in recent years manufacturers have increasingly turned to using multiple smaller tubes fired simultaneously to recreate the big tube effect. So although many of the big CE mines currently on sale might still comprise of a big outer cylinder, inside you will find the powder content is spread across multiple smaller tubes (typically seven, as in the “Mayhem” mine above).
On a technical note, where we talk about “mine effects” in this case we are referring to the overall effect of the firework regardless of whether it delivers that punch from one big mine unit, or from multiple tubes fired together.
You may notice this technical difference too when looking at warning labels; some will refer to the firework as a “mine” and others as a “battery of shot tubes”.