Perfect for machinists, woodworkers, metalworkers and more We offer optional 3 types (A / B / C), you can choose one or more depending on your needs 23 holes include (5) 3/8-16 threaded holes for clamping and (18) undrilled holes for cross drilling design allows efficient use of lighter weight with maximum strength Ground on all 6 sides of the block, accuracy and perpendicularity on all sides range from 0.0001 to 0.0002 in Made of high-quality chrome steel materials, practical and durable, Manufacturer: Vdaxvme