Bolt and spanner set - has bolt head and spanner contoured to prohibit use with normal spanner

摘要

A bolt and activating tool set comprises a contoured bolt head (3), to which the tool (10b) has a matching form. The bolt head has projections (6) and recesses (7) lying in between, which align to longitudinal recesses (12b) in the body of the tool (11b). ADVANTAGE - Bolt turning not possible, or possible in only one direction, with a normal spanner.