From Sapim:

Sapim Leader 13g gauge 2.3mm plain gauge j-bend spokes in Black.

Cut to any length between 50 and 230mm. Cut with a 56tpi thread.

All spokes are custom cut in house on our shear and die equipped spoke cutting and threading machine. We currently offer spokes in sizes from 110-310mm cut to any length you require to the nearest mm.  Threads are rolled, not cut, meaning no stress risers are formed, using exactly the same process as a spoke factory.

These spokes are designed to work with 13g gauge 56 tpi nipples.