Octo 0080110 400 Set Square Folding Mitre/8 ANGLE 400 x 350 mm

The tool is as advertised and has extremely good accuracy when measuring or indicating using it's inside angle, checked with a very accurate bevel gauge set from an equally accurate etched plate showing every angle to half a degree accuracy. Several resets of the Nobex seem to retain this inside-angle accuracy.However, the outside corner of the Nobex is not accurate. At 90 degrees, the outside angle is off such that there's a small gap showing backlight between the Nobex outside long edge and the engineers square used to test it. This same small gap shows with three other squares, all known to be accurate. All the other outside angles are off this teeny bit too.As the inside corner is accurate, this means that either the thin blade or the thicker handle of the Nobex is not the same width along its length. It turns out that it's the shorter arm or handle of the Nobex that varies in width - by 0.1mm between the pivot end and the free end. (4.55mm to 4.45mm).This can be remedied easily enough by taking off that 0.1mm at the free end of the thicker arm of the Nobex, along with a gradually lessening amount towards zero at the pivot end. It can be done using a diamond or water stone; or some fine sandpaper. This does take off the anodised surface, though.I suppose I could return it. But maybe the next one would be the same or worse! So I'll fix it. But only three stars.