The NS Class 3400, referred to as DM'90, was a series of diesel multiple unit which were in service in the Netherlands between 1996 and 2017 and were built by Duewag, Talbot and SIG between 1996 and 1998.

The Class 3400 were the last DMUs in service with NS, the older DE3 "Plan U" and DH1/2 "Wadloper" series having been replaced by the diesel electric Stadler GTW which are still in use with other operators in the Netherlands.

The rolling stock was introduced in the end of the 1990s on a large portion of the non-electrified lines in the Netherlands.

Like the SM'90 ("Railhopper"), the DM'90 uses a non-standard width of 3.2 metres (10 ft 6 in), this was made possible by the distinctly bent side-walls which allowed the cars to be 30 centimetres (11+3⁄4 in) wider than conventional trains while being within the loading gauge.

For cross-border operations out of Heerlen, three sets were equipped with the German PZB train protection system along with boarding steps to accommodate the lower platform height.