Each set comprises two driving end cars (DM1 and DM2) and two intermediate cars (MDT and MT) They are capable of operation as two sets of their own class or in formations of up to 10 cars with either 2600 Class or 2800 Class DMUs. Each car is fitted with a
MAN traction engine and a
Cummins generator engine, both mounted underfloor. Each 4-car set is long, high and wide. They have a maximum permitted speed of . Passenger capacity is 185 seated and 634 standing. The original delivery of twenty sets were numbered 2901-2980. However, when the 2005 batch were ordered, making a total of 116 vehicles, the existing sets were renumbered so that all vehicles would begin with 29: for example, the first set, which had vehicles 2901-2904 was renumbered 29101, 29201, 29301 and 29401; set 2905-2908 was renumbered 29102, 29202, 29302, and 29402. This also avoided conflict with the existing numbering system of the
NIR 3000 Class. The 2005 batch of nine sets were numbered 29x21-29x29 from new. The railcars were the first to be shipped with the new
Commuter branding rather than the "Arrow" branding previously used, and as such were the first Iarnród Éireann rolling stock (other than
DART EMUs and
Enterprise stock) not to feature the company's traditional orange and black livery, which was phased out from passenger service in 2006. The Commuter brand was also extended to the
2600,
2700 and
2800 Class railcars. It has since been replaced by the InterCity livery on these DMUs. In 2014, a new all-over two-tone green livery nicknamed "Green Goddess" was introduced for the class. This was applied to all vehicles by September 2022. ==Deployment==