The structure is strong enough. It's not flimsy and should hold up well. A few years ago I had a similar tool with a loop in the middle so it lay flat when not in use. These must therefore be stored carefully to avoid damage. What I like best is the high print quality. The labels are accurate and easy to use to get very accurate results. - Made of high quality aluminum alloy, so it is wear-resistant, anti-corrosion, durable and high-precision in use. Clear scale markings are accurate and easy to read even in low light. All scales are metric - Hole pattern: There are 9 different hole patterns, suitable for standard drills from 2mm to 10mm - Parallel line drawing function: There are multiple rows of holes for drawing parallel lines. Simply select the appropriate row and mark through the holes to find the line. The two edges are marked with a centimeter scale which can be used to measure or mark points on parallel lines - Angle Finder: A 10-80 degree angle finder is cut into both sides. One edge is marked with an angle scale to find and mark specific angles from 1 to 90 degrees on the work piece - Dovetail Templates: There are two dovetail templates on one side for quick marking of standard dovetails on wood. - This 3D angle ruler is of high quality and suitable for furniture making, DIY projects, woodworking and professional use. Accurate markings provide very accurate results, and the heavy-duty construction means it will last for years. Not sure about the specific use of parallel line holes. Holes may seem less useful than actual lines, but perhaps professional carpenters know better. In general, I like him very much and I will leave him on my bench.