These are COP Basic Weapons Turret Defence System, or BWTDS, or what troops call in slang "Buts". These can go in many places, like installations, vehicles, or just simply on the ground. If your wondering what makes these guys so special is that these turrets are automated. It can hold a 37mm cannon or a .30 caliber machine gun. Depending on your situation.
About this creation
The back view that allows to see more if you wish to make these things.
A look into one of my next MOCs. These turrets attach to motorised vehicles.
I know the vehicle isn't finished, it is just to show what this turret can and will go on. This is another view.