Unlike chains using traditional quick links, NJS chains (like Izumi Super Toughness, D.I.D. Racing Pro and HKK Vertex) feature a tiny bolt and 6mm square nut to affix the chain's ends together.

Made from chrome plated chromoly steel, this incredible little tool features a flat screwdriver head and special magnetic nut holder for quick chain connections and disconnections, eliminating the need to use a screwdriver and pliers.