The Yost 204 4" machinist vise with swivel base has an extra-large jaw opening and throat depth, mounts to a workbench to provide clamping action for heavy-duty applications, meets Federal Specification GGG-V-410B Type VI Class 2. The 360-degree swivel base adjusts the direction of the jaws for proper placement. Hand-tightening the lock knob on the base secures its position. The ductile iron body is durable and strong for extended life. The hardened-steel jaws have grooves for enhanced grip and can be replaced when worn. The jaws draw closer together or farther apart by turning the vise handle clockwise or counterclockwise. The main screw that controls the jaws has been continuous rolled for high strength. A rubber washer on either side of the handle prevents unwanted sliding when turning, and the balls on each end unscrew to enable replacement of the handle if worn. The base has four 0.65"-diameter holes for mounting hardware (not included).