If you need to measure curved objects, this is the right tool. It holds its shape perfectly and is calibrated in metric and imperial units. The gauge doesn't clump up or make it difficult to measure accurately like some other flexible gauges I've tried and discarded. The edges of rule delineation can be right on the edge, which would make this device near perfect. There is about a millimeter of polymerized rubber between the boundary lines and the rim, which is not very accurate for precision work, but is sufficient for my needs. I'm not a machinist and I don't need +-.001 accuracy. The resin is too flexible and won't mold perfectly to your shape without a little work and finesse. It tends to "remember" its previous form, but is still useful.