Body and sliding jaw are manufactured from high quality grey cast iron. This material has excellent shock absorbing qualities. Hardened steel replaceable jaw plates. Slide is precision milled to a high tolerance for a fast smooth operation. For added safety, the tommy bar will bend before the vice becomes over-stressed. Handle and main screw are manufactured from steel. SPECIFICATION: Size:3" Weight:4.8kg Length of JAW Width:75mm (3") Throat depth:48mm Opening:82mm Clamping Force:20kg Size:4" Weight:9.3kg Length of JAW Width:100mm (4") Throat depth:63mm Opening:109mm Clamping Force:25kg Size:5" Weight:15.8kg Length of JAW:Width 125mm (5") Throat depth:73mm Opening:136mm Clamping Force:30kg Size:6" Weight:24.2 Length of JAW Width:150mm (6") Throat depth:86mm Opening:168mm Clamping Force:35mm Size:8" Weight:38.1 Length of JAW Width:200mm (8") Throat depth:103mm Opening:208mm Clamping Force:45kg