Of all the different wood joints you can make, one of the most difficult is one of the simplest - the miter joint.
Here is why the joint can be so frustrating. Let's say you are making a frame and your layout tool or power tool set up is off by 0.003" (0.075 mm) over the width of your joint. That is only three one thousandths of an inch.
If you have ever made a frame where three joints are perfect and the fourth has a bad gap, the problem is likely your 45° reference. That little 0.003" error multiplied by eight cuts means that the fourth corner no features an ugly 0.024" (0.6 mm) gap. The solution often used is to hand fit the last joint by trial and error, but this is avoidable by having an accurate 45° reference to do the layout and/or machine set up.
The MS-2v2 is the largest miter square from Bridge City Tool Works and is excellent for furniture making, architectural work, and other large scale work. Overall Handle Length: 5.74" (145.8 mm). Handle Width: 1.64" (41.7 mm). Handle Thickness: 0.625" (15.9 mm). Overall Blade Length: 11" (279 mm). Blade Width 1.5" (38.1 mm). Blade Thickness 0.06" (1.5 mm).
Like all Bridge City Tool Works Miter Square with handles, it features: