Hexagon key 5mm ISO2936 hardened nickel-plated Hexagon Compatibility: Hexagon key 1.5 for hexagon M2 screws Hexagon key 2.0 for hexagon M3 flat screws Hexagon key 2.5 for hexagon M3 screws and hexagon M4 flat screws Hexagon key 3 for hexagon M4 screws Hexagon key 4 for hexagon M5 screws Hexagon key 5 for G1/8 screw plugs and P&C 1/8? connections Hexagon key 6 for G1/4 screw plugs and P&C ¼? connections Hexagon key 8 for G3/8 screw plugs