First off, I wouldn't take any of the 1-Star reviews for this compass seriously. One of the "1 star reviewers" proposed a test supposedly proving that the circle on circle eclipse system doesn't work. I tried it and have no idea what his point is, as everything checked out fine for me. Other "1-star" reviewers complained of stuff that is easily resolved if you take a little time getting familiar with the 8099.  There were also complaints about some petty things; things that should NOT justify a 1-star rating - more later.