A Machinist Square or Engineer's Square is the Metalworkers' Equivalent of a Try Square.
It Consists of a Steel Blade Inserted and Either Pinned into a Heavier Body at an Angle of 90°. There is Evidence of Pinning at the Intersection of the Blade and Body: the Heads of Three Pins are Visible as Dark Circles. A Small notch has been added to the inside corner of the square to prevent small particles from accumulating and Affecting the Square's Reading. This Notch is Typical of Machinist Squares and is Occasionally Found on Carpentry Squares as well.
Hardened Steel Blade and Polished hair line finish.
 
         1" or 25mm Overall Length 50 x 42mm weight 75gms
         2" or 50mm Overall :ength 75 x 55mm weight 105gms
       3" or 75mm Overall Length 100 x 65mm weight 125gms
       4" or 100mm Overall Length 125 x 80mm weight 145gms
   6" or 150mm Overall Length 180 x 110mm weight 265gms
8" or 200mm Overall Llength  230 x 135mm weight 395gms
9" or 225mm Overall Length  265 x 145mm weight 700gms
10" or 250mm Overall Length  290 x 160mm weight 735gms
12" or 300mm Overall Length  350 x 185mm weight 850gms
18" or 450mm Overall Length  500 x 265mm weight 1500gms
24" or 600mm Overall Length 590 x 345mm weight 3900gms