Since the beginning of metro operation in Bilbao, CAF has supplied various rolling stock to this metropolitan operator. Amongst others, series 500 towing cars and trains have been supplied. These are metric gauge trains made up of four cars, prepared to receive an additional towing car allowing for a final consist of 5 cars. The first deliveres were made between 1995 and 1996. In 2010, new intermediate cars of this series were supplied to the operator.