The invention is a set of two structural tubes joined by an axle with friction bearings. The axle allows the two tube sections to rotate in a plane with respect to each other, producing a relative angle (azimuth) between the two tubes. The axle is made of high strength steel and is threaded. Machined holes are in an evenly distributed pattern on the spines of the tubes. The utility of the invention derives from the uniform section shape of a square tube with a spine, where the spine has a pattern of through holes. The hole pattern is symmetric about the center hole in the pattern. When adjusting the relative angle a between the two structural tubes, four Vernier scales are exposed, two on each structural tube. The four Vernier scales may be viewed for use from the top-left, top-right, bottom-left or bottom-right approach to the device.