Among other things, I use a lathe and need accurate measurements. When I received this there were a few small scratches/chips on the edge of the glass. No big deal. Later, when I needed it, I couldn't get sequential reading at all. The difference was a few thousand or a few tens of thousands every time I tried the same one. My mechanical calipers have been accurate every time. Tried another battery, no change. Put it back in the case, put it in the drawer. Looks good, but is useless as a measuring device.