As the successor to the LSUB, the HSUB combines aspects of several other systems, however the greater size lets it hold vastly more than the LSUB, which was flawed due to the very small amount of space and carrying capacity. Whilst it lacks the stealth found on the predecessor, it has many more weapons and it is capable of making more bloons. Unfortunately it still has the whole "explodes when critically damaged" problem. It's still highly respected regardless. The HSUB is the Heavy Siege Unit Beta. It's a boss of a thing. However unlike the LSUB, these systems aren't miniturised.