History
Professor X designed these lightweight, flexible metal braces for his legs, using a transistorized power source hooked onto his belt to operate them for several hours at a time.[1]
Xavier then used the legs to approach in disguise the Locust.[2]
After a few days, he attempted to use his transistorized leg braces again, but his power source failed.[3]
Later, his Mechanical Legs were once again seen in use to walk to The Warlock's arena.[4]