1-2-3 Blocks Pair 23 Hole with Attachment Hardware Kit

123 blocks coupled with our attachment hardware kit have an almost endless array of uses in the shop. They can be used for machine set up, layout and inspection.   Specifications: 1-2-3 Block Set: 23 Holes:  Made of hardened tool steel (RC 56-60) Precision ground on all six sides. Overall size within +/- 0.0001" (one ten thousandth of an inch) Flatness and parallelism within +/- 0.0001" (one ten thousandth of an inch) Squareness on all sides to within +/- 0.0003" per inch (three ten thousandths of an inch) Pairs are matched to a tolerance of 0.0002" (two ten thousandths of an inch)  Two (2) pieces per set   23 each .340" through holes (5 holes tapped with 3/8" x 16 TPI threads and 18 holes are untapped). Note: these blocks cannot be bolted together without exposed hardware. In order to attach multiple blocks together with no exposed hardware you will require the  Taytools 123 Block Hardware Attachment Kit.   Approximate weight per block: 430 grams/.95 pounds  123 Block Hardware Att