A versatile, classic design, Starrett's standard combination squares are useful for joint layout or machine set-up and as depth, height or marking gauges. They have machined cast-iron heads with a black wrinkle finish and reversible polished steel rules with photo-engraved scales.
Except for the 4" size, each comes with a steel scribing pin and a built-in level vial for determining level or plumb. The 4", 6" and 150mm models are square to within ±0.001" over the full rule length; 12" and 300mm sizes are square to within ±0.002".
Imperial rules are graduated in the 4R style (with increments in 8ths, 16ths, 32nds and 64ths); metric rules are graduated in millimetres and half-millimetres on both faces.
The 4" rule is 1/16" thick by 5/8" wide; the 6" and 150mm rules are 0.080" thick by 3/4"/19mm wide; the 12" and 300mm rules are 0.090" thick by 1"/25mm wide. Rules are straight and parallel within 0.001" per foot.
The four-piece set includes the cast 12" square/miter head and rule, a non-reversible bevel protractor with a level vial and a cast center-finding head, all in a fitted foam-lined hardshell case. The protractor head and center-finding head are also offered separately.