There is a certain group of precision oriented woodworkers (you know who you are!) that absolutely require a precise combination square.
The Starrett 11H 12" Combination Square has a cast iron head. These squares are hefty, handsome and very precise. The milling on the blade is smooth, the matte finish on the square is solid, oiled steel, and the square is square. Each ones is inspected and comes with a signed inspection certificate, which reads:
"Starrett accuracy, finish and design standards are known and respected worldwide. I have inspected this tool to requirements designed to protect our work and reputation."
What is the level of precision, you ask? Well, according to the Starrett catalog, "From a practical point of view, most Starrett mechanical-reading tools are more accurate than the normal eye can read."