If you purchased items from Amazon.com this Cyber Monday, there’s a good chance your purchase was in some way handled by a robot. Amazon’s processing plants in California, Florida, New Jersey, Texas and Washington state employ not only people, but also armies of robots.

The wheeled pods are called Kiva robots from Kiva Systems Inc., which Amazon purchased in 2012 for $775 million, and are the latest innovation to streamline Amazon’s fulfillment processes. The robots, which are a foot tall, 7 feet wide and weigh about 350 pounds, scoot along the floors of Amazon’s processing plants, fetching shelves of products for human employees or putting shelves back in place. They are able to lift 700 to 750 pounds, said Dave Clark, Amazon's senior vice president for worldwide operations and customer service.

Reports in November indicated Amazon planned to equip its facilities with 10,000 Kiva robots by the end of the calendar year, but as of Cyber Monday, approximately 15,000 robots were assisting at 10 Amazon processing plants around the country. However, Kiva robots aren’t exactly intended to replace human employees, just assist them.

“Kiva’s doing the part that’s not that complicated. It’s just moving inventory around,” Clark told Wired. “The person is doing the complicated work, which is reaching in, identifying the right product, making sure it’s the right quality, making sure it’s good enough to be a holiday gift for somebody.”

Clark said eliminating the need for human employees to walk to an aisle to “stow” or “pick” items is beneficial in that it makes the process of moving items more efficient. Additionally, without having to make room for human employees, the isles in Amazon processing plants can be narrower, which would allow locations to hold more products.

For example, the 1.2 million-square-foot OAK4 Amazon Fulfillment Center in Tracy, California, currently has 21 million inventory items, but will hold 26 million when the facility is fully equipped with Kiva robots. This will increase the plant's shipments from 700,000 to approximately 1.5 million, Clark told Wired.

Meanwhile, Clark said he expects the implementation of Kiva robots will in turn increase Amazon’s workforce to maintain the efficiency robots bring. He said 2,500 employees were hired at OAK4 to address the holiday demand, bringing its workforce to 4,000, many of whom may continue to work beyond the holidays.