The term "DigiXros Unit" refers to the various Digimon that serve as components of a DigiXros. Unlike DNA Digivolution, the DigiXros that results from a combination of Digimon depends only on its most basic DigiXros Units and not the immediate components. For example, the Shoutmon X4 DigiXros uses Shoutmon, Ballistamon, Dorulumon, and the Starmons as its basic DigiXros units; however, Shoutmon and Ballistamon can be replaced by Shoutmon X2, or Shoutmon and the Starmons by Shoutmon + Star Sword. When the same DigiXros Units produce a different DigiXros, for instance the five combinations of SkullKnightmon and Axemon, or Shoutmon Star Wheel, these variations are due to the will of the Digimon, and not any differences in their immediate components.