With the help of a robotic exoskeleton, a paralyzed woman from Leicestershire, England, completed a half marathon on Sunday. Thirty-six year-old Claire Lomas wasn’t fast—covering about three miles a day, it took her five days to cross the finish line—but her achievement is still a win for researchers and companies investing in this new technology.

ReWalk Robotics (formerly Argo Medical Technologies), the company that made Lomas’ device, announced last week that it had sold its 100th personal system, a milestone CEO Larry Jasinski said “symbolize[d] a new era” for the company.

One hundred devices may not seem like that many, but each system must be finely customized and calibrated. Leg and hip braces support the wearer, and motors in the braces help lift and rotate joints. Sensors on the hips and knees sense body movement and the wearer uses crutches for balance. “Repeated body shifting generates a sequence of steps which mimics a functional natural gait of the legs,” according to ReWalk website.

As Slate has previously reported, the devices can be prohibitively expensive—one ReWalk systems costs almost $70,000. In February, an insurance company in the U.S. reluctantly agreed to cover the cost of a ReWalk system for one of its clients.

Will Oremus wrote in 2013 that the technology was already being sold to hospitals and clinics around the world and that some companies had even expanded their vision to “commercial exoskeletons and bodysuits aimed at enhancing the strength and endurance of nondisabled people.”

But for Lomas, who was paralyzed from the chest down after a horseback riding accident in 2007, just being able to walk again is enough. She told the BBC that she was “over the moon” about finishing the half marathon, known as the Great North Run. She also walked the London marathon in 2012, with the help of her husband, finishing in 16 days.

But using the exoskeleton is not exactly easy. After the half marathon, she said, “It’s taken some learning. It’s not just physical work, it’s the concentration with every step.”