8 Piece 1-2-3 Precision Block Set & Matched Pair of 1-2-3 Blocks

8 Piece 1-2-3 Precision Block Set & Matched Pair of 1-2-3 Blocks The 23 hole blocks in the 8 piece Precision Block Set include socket screws and a hex key. The blocks in the 8 piece set have an accuracy with squareness on all sides within .0001 per inch. This set is supplied with a fitted case. The other 1-2-3 blocks in the set have a cross drilling design gives minimum weight and maximum strength. The second set has an accuracy with squareness on all sides within .0002 in. per inch. All blocks have 23 holes which consist of 5 tapped holes that are 3/8 in.-16 thread for clamping and 18 untapped holes. All 4 blocks are hardened and precision ground on all 6 sides of each block. Both sets are sold in matched pairs so you will receive 2 matched pairs.