Bought one of these to measure the thickness of convex metal parts. The build quality is good. It's a pretty accurate tool, at least for my purposes. I love how I can pinch it onto a metal plate, bowl, wooden board or similar object by moving the sponges over the object's surface to find areas that are too thick and simply displaying on the watch the LCD screen. . The spacing of the jaws ranges from 0 to 19cm and a 1mm thick piece of metal with a rim of about 5cm by 5cm can reasonably be measured between the jaws ie if you imagine a 5cm by 5cm square torus you can Bring the jaws over and fully close the jaws in the center of the torus. A fairly major annoyance is that the little cart that fits into the side of the blue case doesn't snap into place, causing me to lose the thing when I unnoticed slipped the battery out of its recess. I found the thing again, put the container in the device and taped it in place, problem solved. Still, for the price, it's a pretty good device, at least for my purposes.