[quote=@6slyboy6]
[@Wildman13] "just 2 and a half stories tall."

I feel like they are massive still, but please tell me what exactly is their purpose, if not to shoot down ships in the sky.

[/quote]

Their real purposed is that they are a form of troop transport for the Rarians like the escape method that the Rarians used to escape.

They are oversize cannons designed to launch sky piercer rounds(basically rounds made for boarding ships). though they don't have enough power to hit anything out beyond the stratosphere.

But basically this shells when they hit the ships it will latch onto the ships, giving the Rarians inside enough time to get inside the ships.    

As the exact size of the cannons there are three types of this from the portable ones designed to launch an individual to a certain distance, there are the massive ones that can hit something in the stratosphere. 

for the Rounds they would be the size of a small house just enough to house a giant and a few animal morphs inside.