Simplify the following text for a Grade 7 native English-speaking person.
Original: They are a polycurrent version ( 1500 CV direct current and 25 kV 50 Hz AC ) of the BB 7200 and BB 15000 classes , with which it shares the exterior appearance .
Simplified: They are a dual voltage version ( 1500 V DC and 25 kV 50 Hz AC ) of the BB 7200 and BB 15000 classes .