Allthread is just that. A rod that is threaded from one end to the other. You can get it in many different sizes and threads. It usually comes in 3' lengths and you cut it to whatever length you need. Match the nuts and washers to the allthread that you get. I would put the washers and nuts on each side of the wall that you go through. That way the wall can't flex in either direction. I would also use 1/2-20 rod.Will Home Depot cut all thread for me? What kind of nuts and washers should I use?