These jaws undergo the same hardening and tempering process as our highly acclaimed standard jaw. They will accept hook wire diameters from approximately .040 to .075. The black oxide finish looks clean and reduces glare in the immediate area of your fly. PEAK Saltwater Jaws are available for both the PEAK Rotary Vise (SLT-1) and the PEAK non-Rotary Vise (SLT-NR).