The Sydney Trains A & B sets, also referred to as the Waratah trains, are classes of electric multiple units that currently operate on the Sydney Trains network. Based on the M sets, the Waratahs were manufactured by a joint consortium between CRRC and Downer Rail, with initial construction taking place overseas in Changchun before final assembly at Downer Rail's Cardiff Locomotive Workshops. The sets were named after the Waratah flower, which is the state's floral emblem.

Sydney Trains is the operator and brand name of the train network serving the Greater Sydney metropolitan area in New South Wales, Australia. The network is a hybrid urban-suburban rail system with a central underground core that covers 369 km (229 mi) of route length over 813 km (505 mi) of track, with 170 stations on eight lines.