As with so many Japanese tools this delightful little brass stocked square from Shinwa has been made with considerable thought and attention to detail.
The corner relief is extended where the brass stock meets the stainless steel so that the measuring surfaces are isolated from the area where the blade is riveted to the stock.
Accurate to better than 1/10mm (just a hair under 4 thou), which although not uber-accurate in terms of what is humanly possible at any price - is also more than adequate for a very wide range of tasks.
The inclusion of a hole to hang it on a nail next to a specific task or tool (the bench grinder perhaps?) keeps it ready for convenient use and safe from being knocked.