These British Standards specify materials, dimensions, protective treatment, identification and marking, together with part numbers for hexagon (thick) self-locking nuts, with non-metallic inserts and having MJ screw threads.

They are primarily intended for use on non-structual aerospace applications and have operational temperature limitations of −40 °C to +120 °C.

Coarse thread series for size codes 080, 100 and 120 have been included in Appendix A for those users wishing to specify them.