Biometal Model PX is the Mega Man transformation for Vent (Mega Man) or Aile (Mega Man Zx) from Mega Man ZX by combining Model P (Mega Man) with Model X (Mega Man). It's design takes inspiration from Hidden Phantom (Mega Man) from the Mega Man Zero series.
Similar but not the exact same as Siarnaq's Model P, Model PX can be identified by the arrow design on the helmet present across most biometals combined with Model X.