The E233 class trains were developed by JR East for suburban and commuter trains. They are based on the classes E231 and E531 and consist of sets of four to ten cars each. Each set has two independent equipment sets for redundancy. On each set, all cars except for the end car are powered on all axles. Ten-car trains are also formed from two sets of six and four cars each. There are numerous sub-series for different routes, such as the 2000 series with narrower bodies. In the 3000 series, the ten-car trains each contain two double-deck cars. 