ROSS Try & Mitre SquareProduct Description Try and mitre squares are marking and checking tools used to assess angles and mark straight cuts. They consist of two straight pieces, the stock and the blade, which intersect one other at either 90 or 45. A try square is used for checking right angles (90) and a mitre square is for 45 angles (135 angles are also found on mitre squares because they are created by the 45 intercept).