? Industry s Most Versatile Tool ? Combination squares are commonly used for layout, set-up, checking heights and depths and setting angles. They are also often used as try squares, center gages, bevel protractors and rules. Square Heads and Protractors are supplied with levels. Square Heads also include a hardened steel scriber. Square Heads and Center Heads are available in hardened and non-hardened models. Inch, metric, or inch/metric reading Combination Squares are available in complete sets or components may be purchased separately.