| 300 Series | |
|---|---|
 A 300 Series train on Line H undergoing tests before its introduction. | |
| Manufacturer | Alstom |
| Family name | Alstom Metropolis |
| Constructed | 2014-2019 |
| Entered service | 2016 |
| Number built |  78  42 |
| Number in service | 120 |
| Formation | 6 cars per trainset |
| Capacity | 270 (seated) |
| Operators | Buenos Aires Underground |
| Lines served | |
| Specifications | |
| Car body construction | Stainless steel |
| Car length | 17 m (55 ft 9+1⁄4 in) |
| Width | 2,600 mm (8 ft 6+3⁄8 in) |
| Doors | 4 per side |
| Traction system | Alstom Optonix |
| Electric system(s) | 1500 V DC overhead lines |
| Track gauge | 1,435 mm (4 ft 8+1⁄2 in) standard gauge |
The 300 Series are a set of underground cars manufactured by Alstom in Brazil for use on the Buenos Aires Underground. They are used on Line H of the network, and more have been introduced on Line D where they operate alongside the similar 100 Series.