"Oh yeah. Firs' we presented him with a nice battle helmet -goblin-made an' indestructible, yeh know - an' then we sat down an' we talked.'"
—Hagrid telling Harry, Hermione and Ron about the mission he went on for Dumbledore.[src]

A goblin-made battle helmet was one of the gifts that Rubeus Hagrid and Olympe Maxime brought with them on the diplomatic mission they were assigned by Albus Dumbledore in 1995, which was to recruit the giants to fight with them in the war against Lord Voldemort. It was most likely made to accommodate a giant's size. They presented it to the Gurg, who, at the time of their arrival, was Karkus. After Golgomath killed Karkus and took over as the Gurg, he began wearing the helmet.