Features ul style"margin-top0px; padding-top 5px; padding-bottom 5px;" matched pair & professional quality precision ground steel case hardened on all six sides 1" x 2" x 3" 2 piece pair set square on all sides within 0.0001" 23 holes for easy clamping 5 tapped 3/8"- 16 tpi and 18 plain useful in layout or grinding work hardened and ground steel matched accuracy of .0002" accuracy of .0003" per inch