Stanley Proto nut splitters Stanley Proto nut splitters are designed to remove frozen, corroded or rusted nuts that won't budge. The user places the splitter over the nut and turns the hardened chisel point screw till the nut breaks away from the bolt. The tool is designed to break the nut into easily removed pieces without damaging the bolt that the nut is fastened to. It can be used to split nuts as large as 46 mm or 1-13/16".