Value Collection 0637806/0637801 Setup Block Sets; Type: 1-2-3 & 2-4-6 Block Set ; Squareness Per 1 Inch (Decimal Inch): 0.0003 ; Number of Pieces: 4 ; Tapped Hole Size (Inch): 3/8-16 ; Includes: (1) Pair of 1-2-3 Blocks; (1) Pair of 2-4-6 Blocks ; U