The image shows a Force brand 4-piece nut splitter kit, also identified by the model number 672. Nut splitters are tools used to remove nuts that are rusted, damaged, or seized onto a bolt without damaging the bolt's threads. The tool works by placing the splitter over the nut and tightening a bolt, which forces a cutting wedge into the side of the nut, causing it to split. This allows the nut to be easily removed.