Dee-01's as said, are immobile, and so therefore, can only pivot their turret to any angle, and shoot bullets at the Vic Viper. They are often grouped together, a lot of times guarding the large hatches that release enemies. The Dee-01s located at the bottom of the terrain are particularily easy to kill with Missiles, though the top ones have to be shot at manually. There are red colored Dee-01s that drop power ups, though they are rare.