Game description from the publisher: The Cobra and Rattler Medium Walkers – otherwise known as the MCW M3 Expansion – offer the Allies more options for armored support. With its anti-aircraft gun, the Rattler is capable of grounding airborne units. When it is not punishing aircraft, the Rattler unloads a wall of machine gun fire that shreds infantry to pieces. Meanwhile, the Cobra uses its Phaser gun to electrify vehicles and troops alike, causing massive amounts of damage to both. Additionally, this expansion includes parts to give your walker the Amphibious Unit skill.