These bolts are zinc plated and 3/8 BSW thread.
Overall length is approx 120mm and thread length approx 90mm. The diameter of the bolt material is approx 8.2mm.
They are supplied with two washers, one plain nut and one Nyloc nut.
See article on stay wire supported installations.
Also see :
3 and 4 hook collars
Catenary surface hook