A cylindrical spanner with a hexagonal end fitting over the head of a nut.
More example sentences
- If it's just the switch then I may have wasted 15 quid on a heating element and box spanner I don't need, but since the other element in the tank blew a few months ago, I'm willing to take the risk.
- Having a 52 mm box spanner is a godsend and will make things much easier when reassembling too.
- Standard style torque spanners as well as box spanners for applications with high packing densities are available.