With the help of Jack's engineers, we can build these emplacements to defend our base from aerial attack. Two twin-linked, radar-guided 30mm cannons sure can put up an iron curtain of bullets in the air, but, while quite dependable, this facility is anything but cheap (we gotta pay premium for expertise we don't have ourselves). Also the noise it makes is downright hellish, but, weirdly enough, gals enjoy these places 'for good vibrations'.
Refreshment: 7