23 holes includes ( 5 ) 3 / 8-16 threaded holes for clamping and ( 18 ) untapped holes for Cross drilling design allows for efficient use of lower weight with strength chrome steel materials , practical and Ground on all 6 sides of block , accuracy and squareness on all sides within 0001 " 0002 We 3 kinds optional ( A / B / C ) , you can choose or more according to your needs Perfect for machinists , woodworkers , metalworkers , and more, Manufacturer: Watreketal