1844 W. Pole I. ii. 82 Two plates.., which are bolted together with distance blocks between to keep them parallel with each other.
1979 I. H. Seeley (ed. 3) iv. 42 Bends, hooks, tying wire, distance blocks and ordinary spacers are deemed to be included.
2000 Apr. 167/3 Kistler force plates can be placed between the distance block and the deformable structure.