box spanner

noun

1. a spanner consisting of a steel cylinder with a hexagonal end that fits over a nut: used esp to turn nuts in positions that are recessed or difficult of access

Example Sentences

To facilitate the quick closing of the doors, plates were affixed in suitable positions on the sides of the alleyways, indicating the positions of the deck plates, and a box spanner was provided for each door, hanging in suitable clips alongside the deck plate.

From Project Gutenberg