A simple, recurring problem which I am having trouble solving in OpenCascade: I have an existing STEP file, I load it into OpenCascade. It contains a cylindrical face, which I can interactively select. This face is finite, bounded by two planes. From the TopoDS_Shape representing this cylinder, I need to know its length. I've hunted through the documentation and this forum, and the best I can come up with is to use the TopoExp explorer, search through the shape and find all of its edges, and then try to recognize the two circular edges in that list, then find the distance between them. Haven't tried it, but it sounds like a terrible solution. Does anyone have a better approach??