Wing, the drone delivery company operated by Google parent Alphabet, unveiled a series of new prototype aircraft designed to handle a variety of payloads. The company said the new drones will share the same underlying components with the aircraft currently in use delivering pharmaceuticals and other small packages in the suburbs outside of Dallas-Fort Worth.

According to Wing CEO Adam Woodworth, the aim is to right-size the delivery industry in order to match the appropriate package with a similar sized vehicle. “Just as the ideal vehicle for carrying a ton of gravel would be a dump truck rather than a sedan, the ideal aircraft to carry a bottle of medication is not the same as the best one to deliver a gallon of milk, and neither is suited to deliver a refrigerator,” Woodworth wrote in a blog post.

In a video, the company showed off a variety of different sized drones, including a larger drone that can carry upward of seven pounds and a smaller drone designed to carry prescription medicine weighing up to 0.6 pounds. Wing’s flagship drone is designed to handle payloads of up to 2.5 pounds. The company said that up to 90 percent of deliveries today are packages that weigh five pounds or less, citing comments made by an Amazon executive.

Drone deliveries were supposed to revolutionize the movement of goods around cities, with companies like Amazon and Uber promising to set up large-scale operations in the near future. Instead, the technology has mainly focused on small-scale experiments, delivering vaccines and blood to remote locations.

In the US, drone delivery has generally been limited to smaller towns, where land usage is less crowded and complex. And some companies have faltered in their progress, with Amazon’s program in the UK shedding dozens of employees.

Wing has been able to rack up a series of minor successes, recently completing its 250,000th delivery while operating in three countries: the US, Finland, and Australia. Its biggest success has been in Logan, Australia: a suburb of Brisbane where more than 50,000 of its total deliveries have been carried out.

The company launched its first commercial service in April in the suburban towns of Frisco and Little Elm, both of which are part of the Dallas-Fort Worth metro area. Wing’s operational model involves parking small shipping containers next to participating stores to act as tiny hangers from which Wing’s drones will be deployed. After receiving orders online, employees at each partnering store take the items outside and load them into a cardboard package attached to the drone. Wing’s operations team then pilots the drone remotely to customers’ homes.

Currently, customers can order items from a limited number of stores that are partnering with Wing, including Walgreens, Blue Bell Creameries, Easyvet, and Texas Health. Wing hopes to expand its delivery offerings by introducing different sized aircraft that can handle smaller or bigger packages.

“Aircrafts operate most efficiently around one design point,” Woodworth said. “Big planes carry big stuff, and small planes carry small stuff. For planes like ours, typically that stuff should be about 25 percent of the mass of the plane.”

The company did not disclose the timeline on which it would introduce these new drones, emphasizing that all are still in the prototype phase. Wing isn’t the only company focused on developing drones that can handle heavier packages. Elroy Air is working on a drone that is the size of a small plane and can handle up to 700 pounds of cargo with a range of up to 300 miles.