I don't know why you'd even use it, it costs way too much to focus. Why does it costs an exotic cipher? You already have the exotic engram, it shouldn't cost a cipher ontop of it. They need to go back to the drawing board on that. Idk why they didn't use glass needles. After collecting lets say, all your hunter leg exotics. When it's a leg day for lost sectors, they should drop leg glass needles for you. You take that to rahool and he can reroll exotic legs of your choice for the needle and some materials.