Volvo said Monday that it will sell tens of thousands of vehicles to Uber Technologies that will be the ride-hailing company’s self-driving fleet.

The so-called base vehicles will be developed off car architecture currently used on Volvo’s 90 series cars and the XC60 midsize SUV. Volvo said in a statement that its engineers have worked closely with Uber to develop the technology on another SUV currently on the market.

The autonomous vehicle fleet will number 24,000 vehicles, according to The Wall Street Journal. It’s unclear when the vehicles would be put on the road.

Last year, Uber began offering rides in self-driving Ford Fusions to passengers in Pittsburgh as part of a test of Uber’s self-driving technology. The firm has also opened an advanced technologies group focused on self-driving-technology development, vehicle safety and mapping.