Review on Klein Tools 935AB4V Magnetic V Groove by Jeff Hall

Maybe I misunderstood the description, but this tier is only about 5-6 inches long. Thought it was 9. It's on me. I really like that this thing is magnetic. I'm an electrician so if I'm fitting a panel or meter socket I can attach it directly and don't need another person just to level it. All bottles are clear and easy to see. I still don't understand what the screw at the end is for.