Technical features : * body : made from high strength cast iron and machined within tolerance for accurate fitting of jaws, screw and screw and screw lock hardness 180-210 bhn. * jaws : jaws are made of low carbon case hardening steel and harden in modern heat treatment plant. Jaw's slots are ground for accurate fitting and long life. Hardness 55-60 hrc. * screw : made from case hardening alloy steel and harden and ground bearing areas for longer life. * screw lock : case hardened steel and harden to provide longer life.