I've bent a lot of hard lines in my day, usually with my thumbs and fingers. I finally went out and bought a tubing bender because I see a lot of brake line bending in my near future and I want to make sure I use it properly. What do all of the marks mean on it? I know what the degrees are obviously but on the other side there is O, R, L and another mark I think. So wondering what lining up my mark on tubing with each mark will result in.