Destroyer Droid Battle Launcher
"Destroyer Droids are designed with one function: the complete annihilation of their targets. At the end of heavy arms are immense twin blasters, which unleash destructive energy at a pounding pace. The Destroyer Droid can envelope itself in a globe of protective energy via compact deflector shield generators. Slow and awkard on its three-legged gait, it transforms into a speedier shape by curling into a wheel-shaped form that can roll swiftly on smooth surfaces. In Clone Wars, the Trade Federation uses destroyer droids aboard starships for security and on the ground for combat."