https://phys.org/news/2018-06-army-envision-arm-soldiers.html

"It can help stabilize the weapon and take the load off of their arms," he said. "It's made from composite materials to make it as light as possible, but also to ensure the range of motion that Soldiers need."

Third Arm helps take the weight of the weapons off of a Soldiers' arms. It weighs less than four pounds, but because of the innovative design, the weight of the device and the weapon are evenly distributed.