• Hardened steel set-up, layout and measuring blocks; 1" x 2" x 3"
• 23 clearance holes, five ('X' pattern at center of 3" side) bored with 3/8", 16 TPI threads
• Precision-ground to 0.0003" square and 0.0002" parallel
• Essential measurement & inspection tool for milling, lathes, drilling & jig bores

One-year warranty and Jack's Tool Shed worry-free Satisfaction Guarantee.