Simplify the following text for a Grade 11 native English-speaking person.
Original: The British Rail Class 325 is a dual-voltage alternating current ( AC ) electric multiple unit ( EMU ) train used for postal train services .
Simplified: The British Rail Class 325 is a 4 car dual-voltage 25kV alternating current ( AC ) or 750V direct current ( DC ) electric multiple unit ( EMU ) train used for postal train services .