High quality, long service life, cast CrMo steel construction chain tool for single and multi-speed chains up to 13 speed, including Campangnolo hollow pin chains. Built-in clip holds tool pieces together. Contains 4 and 5mm Allen wrenches and chain hook. CrMo steel chain tool, 4 / 5 mm Allen wrenches, steel wire chain hook Chain hook holder, chain pin holder, and chain pin breaker