University of Utah engineers have built a robotic exoskeleton that gives people with prosthetic legs a power boost that makes walking less difficult.

“It’s equivalent to taking off a 26-pound backpack [while walking],” lead researcher Tommaso Lenzi said in a press release. “That is a really big improvement.”

The challenge: About 220,000 people in the U.S. have had above-knee amputations, meaning their leg was amputated somewhere between the knee and hip.