This is the best way I've found to check the balance of a model both fore and aft and laterally at the same time. The string around the fuselage is a continuous loop so it can slide around the supporting hook in the ceiling to get the model sitting dead level to the floor (both fuselage and wings level). The pointer is a pendulum hanging from the same hook so if the model is laterally unbalanced then it'll point off to the side. A better pointer than mine would be one of those pointy fishing sinkers though.