Calibration is tricky but otherwise good tool
This is a handy accessory for any lathe operator. It seems well made. I found calibration a challenge because it was difficult to center the level bubble and keep it centered while carefully tightening the set screw. I suspect that if you took some modeling clay and used it to hold the bubble vial where you want it before tightening the set screw you might find calibration less exasperating. Overall a good quality product with a modest engineering flaw.