This is a clever piece of technology. Good quality malleable-iron casting, crisp and accurate, with practically no fettling of the working surfaces- white-heart iron probably and it's hollow. It would have been cast round a sand-core which had to be broken up and removed out of the small hole, then heat-treated to remove the brittleness of the cast iron. No moving parts, but will still support the pipe being bent to reduce wall collapse. Why don't you have a go at a bend with it- you might find it works better than your knee!