Abstract: A vises includes a base; a sliding track installed on the base; a lower side of the sliding track being formed with a sliding groove; a main clamping arm extending upwards from the sliding track; a main extension arm extending at an upper side of the main clamping arm; a threaded rod screwed to a threaded hole in the sliding track; a sub-clamping arm extending from an upper side of the sliding body; a sub-extension arm extends from sub-clamping arm and toward the main extension arm of the main clamping arm; a sliding body having a part received in the sliding groove of the sliding track. The main clamping arm is symmetrical to the sub-clamping arm; and therefore, the main extension arm and the sub-extension arm can clamp a large work piece or a standing object steadily with large clamping areas and without releasing.