Biometal Model OX is the Mega Man transformation for Vent (Mega Man) or Aile (Mega Man Zx) from Mega Man ZX by combining Model O (Mega Man) with Model X (Mega Man). It's design is a direct copy of Omega (Mega Man) from the Mega Man Zero series. It allows the user to perform nearly all the special attacks Omega can use.
This is a post-game transformation, and may be considered non-canon due to the circumstances it was acquired in.