These 4 classes are bi-mode, diesel and electric versions of Bombardier's AGC design of 3 or 4-car articulated multiple unit, introduced in 2004. The electric and bi-mode versions are sometimes known as ZGC and BGC respectively. SNCF operates over 700 of the units on regional passenger services.
The B82500 and Z26500 are both capable of working from 1500V DC and 25kV AC systems but the B81500 is 1500V DC only.