Ineffective for light, low tier planes with little upgrade space and already low armour, but great for already heavily armoured planes that could benefit from taking a little less damage in a fight. A hefty range impact and expensive, but the benefits are extreme; when used alone on a 0 Armor Class plane, this upgrade will cause all non-critical flak, autocannon and small machine gun fire to harmlessly bounce from a plane's hull. When used in combination with Wood Reinforced Hull, the combined 17 AC will bounce all pirate machine guns as well.