I gave this five stars because the quality was apparent at first look, the thing is amazing.  I do small projects in my garage using a table saw, radial arm saw and various sanders to make small boxes with multiple sides.  The lids are made of wedges glued together on a backer of the same wood.  In order for sixteen little pieces to fit tightly (eight sided lid) the angles must be exact.  This tool enables me to achieve the accuracy I need.  For those who might wonder, it does come with a pencil that appears to be .05 mm.  Using this instrument I can mark any angle down to .5 degree, using a magnifier I can mark as close as .25 degrees (doubt I can cut that close).  Warning: this protractor is a delicate instrument and needs to be treated as such.  Don't be surprised if you notice smudges when you first begin handling the instrument, this is simply oil from your fingers being transferred to the aluminum.  This bothered me a little so I rubbed it down with a bit of cooking oil and wiped it clean.  I look forward to many years of using this wonderful tool.