Daimler has led a new $17.2 million funding round in Starship Technologies, a startup created by Skype founders Ahti Heinla and Janus Friis, the WSJ reports. The round will help U.K.-based Starship expand its efforts to bring rolling drone deliveries to city sidewalks around the world.

Starship’s six-wheeled autonomous delivery bots are essentially coolers on wheels, keeping contents hot or cold, as well as safe and secure, while bringing them the last mile of their journey to a customer’s doorstep. The drones designed to stick to the ground as a way to simplify the regulatory process, where airborne delivery craft face much more scrutiny and higher standards when it comes to safety requirements before they can enter even supervised trials.

The startup’s delivery bots are equipped with an array of cameras and sensors, and are designed to be tamper-resistant and fine to operate in a variety of weather conditions. They’ve been in testing in both Europe and North America on public streets, and have even begun small-scale commercial service in London as of late last year.

Daimler’s interest in robotic delivery isn’t limited to Starship; it also invested in drone technology startup Matternet, and debuted a drone delivery van concept built using its Mercedes-Benz vehicle platform and the startup’s aerial quadcopters, which it displayed at this year’s CES.